~ILLUSIONS~ _A PSYCHOLOGICAL STUDY_ BY JAMES SULLY AUTHOR OF "SENSATION AND INTUITION, " "PESSIMISM, " ETC. THIRD EDITION LONDON KEGAN PAUL, TRENCH & CO. , 1, PATERNOSTER SQUARE 1887 (_The rights of translation and of reproduction are reserved_) ~THE INTERNATIONAL SCIENTIFIC SERIES. ~ VOL. XXXIV. PREFACE. The present volume takes a wide survey of the field of error, embracingin its view not only the illusions of sense dealt with in treatises onphysiological optics, etc. , but also other errors familiarly known asillusions, and resembling the former in their structure and mode oforigin. I have throughout endeavoured to keep to a strictly scientifictreatment, that is to say, the description and classification ofacknowledged errors, and the explanation of these by a reference totheir psychical and physical conditions. At the same time, I was notable, at the close of my exposition, to avoid pointing out how thepsychology leads on to the philosophy of the subject. Some of thechapters were first roughly sketched out in articles published inmagazines and reviews; but these have been not only greatly enlarged, but, to a considerable extent, rewritten. J. S. _Hampstead, April, 1881. _ CONTENTS. CHAPTER I. THE STUDY OF ILLUSION. Vulgar idea of Illusion, 1, 2; Psychological treatment of subject, 3, 4; definition of Illusion, 4-7; Philosophic extension of idea, 7, 8. CHAPTER II. THE CLASSIFICATION OF ILLUSIONS. Popular and Scientific conceptions of Mind, 9, 10; Illusion and Hallucination, 11-13; varieties of Immediate Knowledge, 13-16; four-fold division of Illusions, 16-18. CHAPTER III. ILLUSIONS OF PERCEPTION: GENERAL. _Psychology of Perception_:--The Psychological analysis of Perception, 19, 20; Sensation and its discrimination, etc. , 20, 21; interpretation of Sensation, 22, 23; construction of material object, 23, 24; recognition of object, specific and individual, 24-27; Preperception and Perception, 27-31; Physiological conditions of Perception, 31-33; Visual and other Sense-perception, 33, 34. _Illusions of Perception_:--Illusion of Perception defined, 35-38; sources of Sense-illusion, 38-40: (a) confusion of Sense-impression, 40-44; (b) misinterpretation of Sense-impression, 44; Passive and Active misinterpretation, 44-46; Passive Illusions as organically and extra-organically conditioned, 46-49. CHAPTER IV. ILLUSIONS OF PERCEPTION--_continued_. A. _Passive Illusions (a) as determined by the Organism. _ _Results of Limits of Sensibility_:--Relation of quantity of Sensation to that of Stimulus, 50-52; coalescence of simultaneous Sensations, 52-55; after-effect of Stimulation, 55, 56; effects of prolonged Stimulation, 56-58; Specific Energy of Nerves, 58, 59; localization of Sensation, 59-62; Subjective Sensations, 62-64. _Results of Variation of Sensibility_:--Rise and fall of Sensibility, 64-67; Paræsesthesia, 67, 68; _rationale_ of organically conditioned Illusions, 68, 69. CHAPTER V. ILLUSIONS OF PERCEPTION--_continued_. A. _Passive Illusions (b) as determined by the Environment. _ _Exceptional Relation of Stimulus to Organ_:--Displacement of organ, etc. , 70-72. _Exceptional Arrangement of Circumstances in the Environment_:-- Misinterpretation of the direction and movement of objects, 72-75; misperception of Distance, 75, 76; Illusions of depth, relief, and solidity in Art, 77-81; Illusions connected with the perception of objects through transparent coloured media, 82-84; visual transformation of concave into convex form, 84-86; false recognition of objects, 86, 87; inattention to Sense-impression in Recognition, 87-91; suggestion taking the direction of familiar recurring experiences, 91, 92. CHAPTER VI. ILLUSIONS OF PERCEPTION--_continued_. B. _Active Illusions. _ Preperception and Illusion, 93-95. _Voluntary Preperception_:--Choice of interpretation in the case of visible movement, 95, 96; and in the case of flat projections of form, 96-98; capricious interpretation of obscure impressions, 99, 100. _Involuntary Preperception_:--Effects of permanent Predisposition, 101, 102; effects of partial temporary Preadjustment, 102-105; complete Pro-adjustment or Expectation, 106-109; subordination of Sense-impression to Preperception, 109-111; transition from Illusion to Hallucination, 111, 112; rudimentary Hallucinations, 112-114; developed Hallucinations, 114-116; Hallucination in normal life, 116, 117; Hallucinations of insanity, 118-120; gradual development of Sense-illusions, and continuity of normal and abnormal life; 120-123; Sanity and Insanity distinguished, 123-126. CHAPTER VII. DREAMS. Mystery of sleep, 127, 128; theories of Dreams, 128, 129; scientific explanation of Dreams, 129, 130. _Sleep and Dreaming_:--Condition of organism during sleep, 131, 132; Are the nervous centres ever wholly inactive during sleep? 132-134; nature of cerebral activity involved in Dreams, 134-136; psychical conditions of Dreams, 136-138. _The Dream as Illusion_:--External Sense-impressions as excitants of Dream-images, 139-143; internal "subjective" stimuli in the sense-organs, 143-145; organic sensations, 145-147; how sensations are exaggerated in Dream-interpretation, 147-151. _The Dream as Hallucination_:--Results of direct central stimulation 151-153; indirect central stimulation and association, 153-155. _The Form and Structure of Dreams_:--The incoherence of Dreams explained, 156-161; coherence and unity of Dream as effected (a) by coalescence and transformation of images, 161-163; (b) by aground-tone of feeling, 164-168; (c) by the play of associative dispositions, 168-172; (d) by the activities of selective attention stimulated by the rational impulse to connect and to arrange, 172-176; examples of Dreams, 176-179; limits of intelligence and rational activity in Dreams, 180-182; Dreaming and mental disease, 182, 183; After-dreams and Apparitions, 183-185. NOTE. --The Hypnotic Condition, 185-188. CHAPTER VIII. ILLUSIONS OF INTROSPECTION. Illusions of Introspection defined, 189-192; question of the possibility of illusory Introspection, 192-194; incomplete grasp of internal feelings as such, 194-196; misobservation of internal feelings: Passive Illusions, 196-199; Active Illusions, 199-202; malobservation of subjective states, 202-205; Illusory Introspection in psychology and philosophy, 205-208; value of the Introspective method, 208-211. CHAPTER IX. OTHER QUASI-PRESENTATIVE ILLUSIONS: ERRORS OF INSIGHT. Emotion and Perception, 212; Æsthetic Intuition, 213; Subjective Impressions of beauty misinterpreted, 213-216; analogous Emotional Intuitions, 216, 217; Insight, its nature, 217-220; Passive Illusions of Insight, 220-222; Active Illusions of Insight: projection of individual feelings, 222-224; the poetic transformation of nature, 224-226; special predispositions as falsifying Insight, 226-228; value of faculty of Insight, 228-230. CHAPTER X. ILLUSIONS OF MEMORY. Vulgar confidence in Memory, 231-233; definition of Memory, 233-235; Psychology of Memory, 235-237; Physiology of Memory, 237, 238; Memory as localization in the past, 238-241; Illusions of Memory classified, 241-245. (1) _Illusions of Time-Perspective_:-- (a) Definite Localization of events: constant errors in retrospective estimate of time, 245-249; varying errors: estimate of duration during a period, 249-251; variations in retrospective estimate of duration, 251-256. (b) Indefinite Localization: effect of vividness of mnemonic image on the apparent distance of events, 256-258; isolated public events, 258, 259; active element in errors of Localization, 259-261. (2) _Distortions of Memory_:--Transformation of past through forgetfulness, 261-264; confusion of distinct recollections, 264-266; Active Illusion: influence of present imaginative activity, 266-269; exaggeration in recollections of remote experiences, 269, 270; action of present feeling in transforming past, 270, 271. (3) _Hallucinations of Memory_:--Their nature, 271-273; past dreams taken for external experiences, 273-277; past waking imagination taken for external reality, 277-280; recollection of prenatal ancestral experience, 280, 281; filling up gaps in recollection, 281-283. _Illusions connected with, Personal Identity_:--Illusions of Memory and Sense of identity, 283, 284; idea of permanent self, how built up, 285-287; disturbances of sense of identity, 287-290; fallibility and trustworthiness of Memory, 290-292. NOTE. --Momentary Illusions of Self-consciousness, 293. CHAPTER XI. ILLUSIONS OF BELIEF. Belief as Immediate or Intuitive, 294-296; simple and compound Belief, 296. A. _Simple Illusory Belief_:-- (1) Expectation: its nature, 297, 298; Is Expectation ever intuitive? 298; Expectation and Inference from the past, 299-301; Expectation of new kinds of experience, 301, 302; Permanent Expectations of remote events, 302; misrepresentation of future duration, 302-305; Imaginative transformation of future, 305-307. (2) Quasi-Expectations: anticipation of extra-personal experiences, 307, 308; Retrospective Beliefs, 308-312. B. _Compound Illusory Belief_:-- (1) Representations of permanent things: their structure, 312; our representations of others as illusory, 312-315; our representation of ourselves as illusory, 315; Illusion of self-esteem, 316-318; genesis of illusory opinion of self, 318-322; Illusion in our representations of classes of things, 322, 323; and in our views of the world as a whole, 323, 324; tendency of belief towards divergence, 325; and towards convergence, 326, 327. CHAPTER XII. RESULTS. Range of Illusion, 328-330; nature and causes of Illusion in general, 331-334; Illusion identical with Fallacy, 334; Illusion as abnormal, 336, 337; question of common error, 337-339; evolutionist's conception of error as maladaptation, 339-344; common intuitions tested only by philosophy, 344; assumptions of science respecting external reality, etc. , 344-346; philosophic investigation of these assumptions, 346-348; connection between scientific and philosophic consideration of Illusion, 348-350; correction of Illusion and its implications, 351, 352; Fundamental Intuitions and modern psychology, 352; psychology as positive science and as philosophy, 353-355; points of resemblance between acknowledged Illusions and Fundamental Intuitions, 355, 356; question of origin, and question of validity, 356, 357; attitude of scientific mind towards philosophic scepticism, 357-360; Persistent Intuitions must be taken as true, 360, 361. ~ILLUSIONS. ~ CHAPTER I. THE STUDY OF ILLUSION. Common sense, knowing nothing of fine distinctions, is wont to draw asharp line between the region of illusion and that of sane intelligence. To be the victim of an illusion is, in the popular judgment, to beexcluded from the category of rational men. The term at once calls upimages of stunted figures with ill-developed brains, half-wittedcreatures, hardly distinguishable from the admittedly insane. And thisway of thinking of illusion and its subjects is strengthened by one ofthe characteristic sentiments of our age. The nineteenth centuryintelligence plumes itself on having got at the bottom of mediævalvisions and church miracles, and it is wont to commiserate the feebleminds that are still subject to these self-deceptions. According to this view, illusion is something essentially abnormal andallied to insanity. And it would seem to follow that its nature andorigin can be best studied by those whose speciality it is to observethe phenomena of abnormal life. Scientific procedure has in the mainconformed to this distinction of common sense. The phenomena of illusionhave ordinarily been investigated by alienists, that is to say, physicians who are brought face to face with their most striking formsin the mentally deranged. While there are very good reasons for this treatment of illusion as abranch of mental pathology, it is by no means certain that it can be acomplete and exhaustive one. Notwithstanding the flattering suppositionof common sense, that illusion is essentially an incident in abnormallife, the careful observer knows well enough that the case is farotherwise. There is, indeed, a view of our race diametrically opposed to theflattering opinion referred to above, namely, the humiliating judgmentthat all men habitually err, or that illusion is to be regarded as thenatural condition of mortals. This idea has found expression, not onlyin the cynical exclamation of the misanthropist that most men are fools, but also in the cry of despair that sometimes breaks from the wearysearcher after absolute truth, and from the poet when impressed with theunreality of his early ideals. Without adopting this very disparaging opinion of the intellectualcondition of mankind, we must recognize the fact that most men aresometimes liable to illusion. Hardly anybody is always consistentlysober and rational in his perceptions and beliefs. A momentary fatigueof the nerves, a little mental excitement, a relaxation of the effort ofattention by which we continually take our bearings with respect to thereal world about us, will produce just the same kind of confusion ofreality and phantasm, which we observe in the insane. To give but anexample: the play of fancy which leads to a detection of animal andother forms in clouds, is known to be an occupation of the insane, andis rightly made use of by Shakespeare as a mark of incipient mentalaberration in Hamlet; and yet this very same occupation is quite naturalto children, and to imaginative adults when they choose to throw thereins on the neck of their phantasy. Our luminous circle of rationalperception is surrounded by a misty penumbra of illusion. Common senseitself may be said to admit this, since the greatest stickler for theenlightenment of our age will be found in practice to accuse most of hisacquaintance at some time or another of falling into illusion. If illusion thus has its roots in ordinary mental life, the study of itwould seem to belong to the physiology as much as to the pathology ofmind. We may even go further, and say that in the analysis andexplanation of illusion the psychologist may be expected to do more thanthe physician. If, on the one hand, the latter has the great privilegeof observing the phenomena in their highest intensity, on the otherhand, the former has the advantage of being familiar with the normalintellectual process which all illusion simulates or caricatures. Tothis it must be added that the physician is naturally disposed to lookat illusion mainly, if not exclusively, on its practical side, that is, as a concomitant and symptom of cerebral disease, which it is needful tobe able to recognize. The psychologist has a different interest in thesubject, being specially concerned to understand the mental antecedentsof illusion and its relation to accurate perception and belief. It ispretty evident, indeed, that the phenomena of illusion form a regioncommon to the psychologist and the mental pathologist, and that thecomplete elucidation of the subject will need the co-operation of thetwo classes of investigator. In the present volume an attempt will be made to work out thepsychological side of the subject; that is to say, illusions will beviewed in their relation to the process of just and accurate perception. In the carrying out of this plan our principal attention will be givento the manifestations of the illusory impulse in normal life. At thesame time, though no special acquaintance with the pathology of thesubject will be laid claim to, frequent references will be made to theillusions of the insane. Indeed, it will be found that the two groups ofphenomena--the illusions of the normal and of the abnormalcondition--are so similar, and pass into one another by such insensiblegradations, that it is impossible to discuss the one apart from theother. The view of illusion which will be adopted in this work is thatit constitutes a kind of border-land between perfectly sane and vigorousmental life and dementia. And here at once there forces itself on our attention the question, Whatexactly is to be understood by the term "illusion"? In scientific workstreating of the pathology of the subject, the word is confined to whatare specially known as illusions of the senses, that is to say, to falseor illusory perceptions. And there is very good reason for thislimitation, since such illusions of the senses are the most palpableand striking symptoms of mental disease. In addition to this, it must beallowed that, to the ordinary reader, the term first of all calls upthis same idea of a deception of the senses. At the same time, popular usage has long since extended the term so asto include under it errors which do not counterfeit actual perceptions. We commonly speak of a man being under an illusion respecting himselfwhen he has a ridiculously exaggerated view of his own importance, andin a similar way of a person being in a state of illusion with respectto the past when, through frailty of memory, he pictures it quiteotherwise than it is certainly known to have been. It will be found, I think, that there is a very good reason for thispopular extension of the term. The errors just alluded to have this incommon with illusions of sense, that they simulate the form of immediateor self-evident cognition. An idea held respecting ourselves orrespecting our past history does not depend on any other piece ofknowledge; in other words, is not adopted as the result of a process ofreasoning. What I believe with reference to my past history, so far as Ican myself recall it, I believe instantaneously and immediately, withoutthe intervention of any premise or reason. Similarly, our notions ofourselves are, for the most part, obtained apart from any process ofinference. The view which a man takes of his own character or claims onsociety he is popularly supposed to receive intuitively by a mere act ofinternal observation. Such beliefs may not, indeed, have all theoverpowering force which belongs to illusory perceptions, for theintuition of something by the senses is commonly looked on as the mostimmediate and irresistible kind of knowledge. Still, they must be saidto come very near illusions of sense in the degree of their self-evidentcertainty. Taking this view of illusion, we may provisionally define it as anyspecies of error which counterfeits the form of immediate, self-evident, or intuitive knowledge, whether as sense-perception or otherwise. Whenever a thing is believed on its own evidence and not as a conclusionfrom something else, and the thing then believed is demonstrably wrong, there is an illusion. The term would thus appear to cover all varietiesof error which are not recognized as fallacies or false inferences. Iffor the present we roughly divide all our knowledge into the two regionsof primary or intuitive, and secondary or inferential knowledge, we seethat illusion is false or spurious knowledge of the first kind, fallacyfalse or spurious knowledge of the second kind. At the same time, it isto be remembered that this division is only a very rough one. As willappear in the course of our investigation, the same error may be calledeither a fallacy or an illusion, according as we are thinking of itsoriginal mode of production or of the form which it finally assumes; anda thorough-going psychological analysis of error may discover that thesetwo classes are at bottom very similar. As we proceed, we shall, I think, find an ample justification for ourdefinition. We shall see that such illusions as those respectingourselves or the past arise by very much the same mental processes asthose which are discoverable in the production of illusory perceptions;and thus a complete psychology of the one class will, at the same time, contain the explanation of the other classes. The reader is doubtless aware that philosophers have still furtherextended the idea of illusion by seeking to bring under it beliefs whichthe common sense of mankind has always adopted and never begun tosuspect. Thus, according to the idealist, the popular notion (theexistence of which Berkeley, however, denied) of an external world, existing in itself and in no wise dependent on our perceptions of it, resolves itself into a grand illusion of sense. At the close of our study of illusions we shall return to this point. Weshall there inquire into the connection between those illusions whichare popularly recognized as such, and those which first come into viewor appear to do so (for we must not yet assume that there are such)after a certain kind of philosophic reflection. And some attempt will bemade to determine roughly how far the process of dissolving thesesubstantial beliefs of mankind into airy phantasms may venture to go. For the present, however, these so-called illusions in philosophy willbe ignored. It is plain that illusion exists only in antithesis to realknowledge. This last must be assumed as something above all question. And a rough and provisional, though for our purpose sufficientlyaccurate, demarcation of the regions of the real and the illusory seemsto coincide with the line which common sense draws between what allnormal men agree in holding and what the individual holds, whethertemporarily or permanently, in contradiction to this. For our presentpurpose the real is that which is true for all. Thus, though physicalscience may tell us that there is nothing corresponding to oursensations of colour in the world of matter and motion which itconceives as surrounding us; yet, inasmuch as to all men endowed withthe normal colour-sense the same material objects appear to have thesame colour, we may speak of any such perception as practically true, marking it off from those plainly illusory perceptions which are due tosome subjective cause, as, for example, fatigue of the retina. To sum up: in treating of illusions we shall assume, what science asdistinguished from philosophy is bound to assume, namely, that humanexperience is consistent; that men's perceptions and beliefs fall into aconsensus. From this point of view illusion is seen to arise throughsome exceptional feature in the situation or condition of theindividual, which, for the time, breaks the chain of intellectualsolidarity which under ordinary circumstances binds the single member tothe collective body. Whether the common experience which men thus obtainis rightly interpreted is a question which does not concern us here. Forour present purpose, which is the determination and explanation ofillusion as popularly understood, it is sufficient that there is thisgeneral consensus of belief, and this may provisionally be regarded asat least practically true. CHAPTER II. THE CLASSIFICATION OF ILLUSIONS. If illusion is the simulation of immediate knowledge, the most obviousmode of classifying illusions would appear to be according to thevariety of the knowledge which they simulate. Now, the popular psychology that floats about in the ordinary forms oflanguage has long since distinguished certain kinds of unreasoned oruninferred knowledge. Of these the two best known are perception andmemory. When I see an object before me, or when I recall an event in mypast experience, I am supposed to grasp a piece of knowledge directly, to know something immediately, and not through the medium of somethingelse. Yet I know differently in the two cases. In the first I know bywhat is called a presentative process, namely, that of sense-perception;in the second I know by a representative process, namely, that ofreproduction, or on the evidence of memory. In the one case the objectof cognition is present to my perceptive faculties; in the other it isrecalled by the power of memory. Scientific psychology tends, no doubt, to break down some of thesepopular distinctions. Just as the zoologist sometimes groups togethervarieties of animals which the unscientific eye would never think ofconnecting, so the psychologist may analyze mental operations whichappear widely dissimilar to the popular mind, and reduce them to onefundamental process. Thus recent psychology draws no sharp distinctionbetween perception and recollection. It finds in both very much the sameelements, though combined in a different way. Strictly speaking, indeed, perception must be defined as a presentative-representative operation. To the psychologist it comes to very much the same thing whether, forexample, on a visit to Switzerland, our minds are occupied in_perceiving_ the distance of a mountain or in _remembering_ somepleasant excursion which we made to it on a former visit. In both casesthere is a reinstatement of the past, a reproduction of earlierexperience, a process of adding to a present impression a product ofimagination--taking this word in its widest sense. In both cases thesame laws of reproduction or association are illustrated. Just as a deep and exhaustive analysis of the intellectual operationsthus tends to identify their various forms as they are distinguished bythe popular mind, so a thorough investigation of the flaws in theseoperations, that is to say, the counterfeits of knowledge, will probablylead to an identification of the essential mental process whichunderlies them. It is apparent, for example, that, whether a man_projects_ some figment of his imagination into the external world, giving it, present material reality, or whether (if I may be allowed theterm) he _retrojects_ it into the dim region of the past, and takes itfor a reality that has been he is committing substantially the sameblunder. The source of the illusion in both cases is one and the same. It might seem to follow from this that a scientific discussion of thesubject would overlook the obvious distinction between illusions ofperception and those of memory; that it would attend simply todifferences in the mode of origination of the illusion, whatever itsexternal form. Our next step, then, would appear to be to determinethese differences in the mode of production. That there are differences in the origin and source of illusion is afact which has been fully recognized by those writers who have made aspecial study of sense-illusions. By these the term illusion is commonlyemployed in a narrow, technical sense, and opposed to hallucination. Anillusion, it is said, must always have its starting-point in some actualimpression, whereas a hallucination has no such basis. Thus it is anillusion when a man, under the action of terror, takes a stump of atree, whitened by the moon's rays, for a ghost. It is a hallucinationwhen an imaginative person so vividly pictures to himself the form ofsome absent friend that, for the moment, he fancies himself actuallybeholding him. Illusion is thus a partial displacement of external factby a fiction of the imagination, while hallucination is a totaldisplacement. This distinction, which has been adopted by the majority of recentalienists[1], is a valuable one, and must not be lost sight of here. Itwould seem, from a psychological point of view, to be an importantcircumstance in the genesis of a false perception whether theintellectual process sets out from within or from without. And it willbe found, moreover, that this distinction may be applied to all thevarieties of error which I propose to consider. Thus, for example, itwill be seen further on that a false recollection may set out eitherfrom the idea of some actual past occurrence or from a present productof the imagination. It is to be observed, however, that the line of separation betweenillusion and hallucination, as thus defined, is a very narrow one. In byfar the largest number of hallucinations it is impossible to prove thatthere is no modicum of external agency co-operating in the production ofthe effect. It is presumable, indeed, that many, if not all, hallucinations have such a basis of fact. Thus, the madman who projectshis internal thoughts outwards in the shape of external voices may, foraught we know, be prompted to do so in part by faint impressions comingfrom the ear, the result of those slight stimulations to which the organis always exposed, even in profound silence, and which in his caseassume an exaggerated intensity. And even if it is clearly made out thatthere are hallucinations in the strict sense, that is to say, falseperceptions which are wholly due to internal causes, it must be concededthat illusion shades off into hallucination by steps which it isimpossible for science to mark. In many cases it must be left an openquestion whether the error is to be classed as an illusion or as ahallucination. [2] For these reasons, I think it best not to make the distinction betweenillusion and hallucination the leading principle of my classification. However important psychologically, it does not lend itself to thispurpose. The distinction must be kept in view and illustrated as far aspossible. Accordingly, while in general following popular usage andemploying the term illusion as the generic name, I shall, whenconvenient, recognize the narrow and technical sense of the term asanswering to a species co-ordinate with hallucination. Departing, then, from what might seem the ideally best order ofexposition, I propose, after all, to set out with the simple popularscheme of faculties already referred to. Even if they are, psychologically considered, identical operations, perception and memoryare in general sufficiently marked off by a speciality in the form ofthe operation. Thus, while memory is the reproduction of something witha special reference of consciousness to its past existence, perceptionis the reproduction of something with a special reference to its presentexistence as a part of the presented object. In other words, thoughlargely _representative_ when viewed as to its origin, perception is_presentative_ in relation to the object which is supposed to beimmediately present to the mind at the moment. [3] Hence the convenienceof recognizing the popular classification, and of making it ourstarting-point in the present case. All knowledge which has any appearance of being directly reached, immediate, or self-evident, that is to say, of not being inferred fromother knowledge, may be divided into four principal varieties: InternalPerception or Introspection of the mind's own feelings;External Perception; Memory; and Belief, in so far as it simulates theform of direct knowledge. The first is illustrated in a man'sconsciousness of a present feeling of pain or pleasure. The second andthe third kinds have already been spoken of, and are too familiar torequire illustration. It is only needful to remark here that, underperception, or rather in close conjunction with it, I purpose dealingwith the knowledge of other's feelings, in so far as this assumes theaspect of immediate knowledge. The term belief is here used to includeexpectations and any other kinds of conviction that do not fall underone of the other heads. An instance of a seemingly immediate beliefwould be a prophetic prevision of a coming disaster, or a man'sunreasoned persuasion as to his own powers of performing a difficulttask. It is, indeed, said by many thinkers that there are no legitimateimmediate beliefs; that all our expectations and other convictions aboutthings, in so far as they are sound, must repose on other genuinelyimmediate knowledge, more particularly sense-perception and memory. This difficult question need not be discussed here. It is allowed by allthat there is a multitude of beliefs which we hold tenaciously and onwhich we are ready to act, which, to the mature mind, wear theappearance of intuitive truths, owing their cogency to nothing beyondthemselves. A man's belief in his own merits, however it may have beenfirst obtained, is as immediately assured to him as his recognition of areal object in the act of sense-perception. It may be added that many ofour every-day working beliefs about the world in which we live, thoughpresumably derived from memory and perception, tend to lose all tracesof their origin, and to simulate the aspect of intuitions. Thus theproposition that logicians are in the habit of pressing on ourattention, that "Men are mortal, " seems, on the face of it, to commonsense to be something very like a self-evident truth, not depending onany particular facts of experience. In calling these four forms of cognition immediate, I must not, however, be supposed to be placing them on the same logical level. It is plain, indeed, to a reflective mind that, though each may be called immediatein this superficial sense, there are perceptible differences in thedegree of their immediacy. Thus it is manifest, after a moment'sreflection, that expectation, so far as it is just, is not primarilyimmediate in the sense in which purely presentative knowledge is so, since it can be shown to follow from something else. So a generalproposition, though through familiarity and innumerable illustrations ithas acquired a self-evident character, is seen with a very littleinspection to be less fundamentally and essentially so than theproposition, "I am now feeling pain;" and it will be found that evenwith respect to memory, when the remembered event is at all remote, theprocess of cognition approximates to a mediate operation, namely, one ofinference. What the relative values of these different kinds ofimmediate knowledge are is a point which will have to be touched on atthe end of our study. Here it must suffice to warn the reader againstthe supposition that this value is assumed to be identical. It might seem at a first glance to follow from this four-fold scheme ofimmediate or quasi-immediate knowledge that there are four varieties ofillusion. And this is true in the sense that these four heads cover allthe main varieties of illusion. If there are only four varieties ofknowledge which can lay any claim to be considered immediate, it must bethat every illusion will simulate the form of one of these varieties, and so be referable to the corresponding division. But though there are conceivably these four species of illusion, it doesnot follow that there are any actual instances of each classforthcoming. This we cannot determine till we have investigated thenature and origin of illusory error. For example, it might be found thatintrospection, or the immediate inspection of our own feelings or mentalstates, does not supply the conditions necessary to the production ofsuch error. And, indeed, it is probable that most persons, antecedentlyto inquiry, would be disposed to say that to fall into error in theobservation of what is actually going on in our own minds isimpossible. With the exception of this first division, however, this scheme mayeasily be seen to answer to actual phenomena. That there are illusionsof perception is obvious, since it is to the errors of sense that theterm illusion has most frequently been confined. It is hardly lessevident that there are illusions of memory. The peculiar difficulty ofdistinguishing between a past real event and a mere phantom of theimagination, illustrated in the exclamation, "I either saw it or dreamtit, " sufficiently shows that memory is liable to be imposed on. Finally, it is agreed on by all that the beliefs we are wont to regard asself-evident are sometimes erroneous. When, for example, an imaginativewoman says she knows, by mere intuition, that something interesting isgoing to happen, say the arrival of a favourite friend, she is plainlyrunning the risk of being self-deluded. So, too, a man's estimate ofhimself, however valid for him, may turn out to be flagrantly false. In the following discussion of the subject I shall depart from the aboveorder in so far as to set out with illusions of sense-perception. Theseare well ascertained, forming, indeed, the best-marked variety. And theexplanation of these has been carried much further than that of theothers. Hence, according to the rule to proceed from the known to theunknown, there will be an obvious convenience in examining these firstof all. After having done this, we shall be in a position to inquirewhether there is anything analogous in the region of introspection orinternal perception. Our study of the errors of sense-perception will, moreover, prove the best preparation for an inquiry into the nature andmode of production of the remaining two varieties. [4] I would add that, in close connection with the first division, illusionsof perception, I shall treat the subtle and complicated phenomena ofdreams. Although containing elements which ought, according tostrictness, to be brought under one of the other heads, they are, astheir common appellation, "visions, " shows, largely simulations ofexternal, and more especially visual, perception. Dreams are no doubt sharply marked off from illusions ofsense-perception by a number of special circumstances. Indeed, it may bethought that they cannot be adequately treated in a work that aimsprimarily at investigating the illusions of normal life, and shouldrather be left to those who make the pathological side of the subjecttheir special study. Yet it may, perhaps, be said that in a wide sensedreams are a feature of normal life. And, however this be, they havequite enough in common with other illusions of perception to justify usin dealing with them in close connection with these. CHAPTER III. ILLUSIONS OF PERCEPTION: GENERAL. The errors with which we shall be concerned in this chapter are thosewhich are commonly denoted by the term illusion, that is to say, thoseof sense. They are sometimes called deceptions of the senses; but thisis a somewhat loose expression, suggesting that we can be deceived as tosensation itself, though, as we shall see later on, this is only true ina very restricted meaning of the phrase. To speak correctly, sense-illusions must be said to arise by a simulation of the form ofjust and accurate perceptions. Accordingly, we shall most frequentlyspeak of them as illusions of perception. In order to investigate the nature of any kind of error, it is needfulto understand the kind of knowledge it imitates, and so we must beginour inquiry into the nature of illusions of sense by a brief account ofthe psychology of perception; and, in doing this, we shall proceed bestby regarding this operation in its most complete form, namely, that ofvisual perception. I may observe that in this analysis of perception I shall endeavour tokeep to known facts, namely, the psychical phenomena or events whichcan be seen by the methods of scientific psychology to enter into themental content called the percept. I do not now inquire whether such ananalysis can help us to understand all that is meant by perception. Thispoint will have to be touched later on. Here it is enough to say that, whatever our philosophy of perception may be, we must accept thepsychological fact that the concrete mental state in the act ofperception is built up out of elements, the history of which can betraced by the methods of mental science. _Psychology of Perception. _ Confining ourselves for the present to the mental, as distinguished fromthe physical, side of the operation, we soon find that perception is notso simple a matter as it might at first seem to be. When a man on a hotday looks at a running stream and "sees" the delicious coolness, it isnot difficult to show that he is really performing an act of mentalsynthesis, or imaginative construction. To the sense-impression[5] whichhis eye now gives him, he adds something which past experience hasbequeathed to his mind. In perception, the material of sensation isacted on by the mind, which embodies in its present attitude all theresults of its past growth. Let us look at this process of synthesis alittle more closely. When a sensation arises in the mind, it may, under certaincircumstances, go unattended to. In that case there is no perception. The sensation floats in the dim outer regions of consciousness as avague feeling, the real nature and history of which are unknown. Thisremark applies not only to the undefined bodily sensations that arealways oscillating about the threshold of obscure consciousness, but tothe higher sensations connected with the special organs of perception. The student in optics soon makes the startling discovery that his fieldof vision has all through his life been haunted with weird shapes whichhave never troubled the serenity of his mind just because they havenever been distinctly attended to. The immediate result of this process of directing the keen glance ofattention to a sensation is to give it greater force and distinctness. By attending to it we discriminate it from other feelings present andpast, and classify it with like sensations previously received. Thus, ifI receive a visual impression of the colour orange, the firstconsequence of attending to it is to mark it off from othercolour-impressions, including those of red and yellow. And inrecognizing the peculiar quality of the impression by applying to it theterm orange, I obviously connect it with other similar sensations calledby the same name. If a sensation is perfectly new, there cannot, ofcourse, be this process of classifying, and in this case the closelyrelated operation of discriminating it from other sensations is lessexactly performed. But it is hardly necessary to remark that, in themind of the adult, under ordinary circumstances, no perfectly newsensation ever occurs. When the sensation, or complex sensation, is thus defined andrecognized, there follows the process of interpretation, by which I meanthe taking up of the impression as an element into the complex mentalstate known as a percept. Without going into the philosophical questionof what this process of synthesis exactly means, I may observe that, bycommon consent, it takes place to a large extent by help of areproduction of sensations of various kinds experienced in the past. That is to say, the details in this act of combination are drawn fromthe store of mental recollections to which the growing mind is everadding. In other words, the percept arises through a fusion of an actualsensation with mental representations or "images" of sensation. [6] Everyelement of the object that we thus take up in the act of perception, orput into the percept, as its actual size, distance, and so on, will befound to make itself known to us through mental images or revivals ofpast experiences, such as those we have in handling the object, movingto and from it, etc. It follows that if this is an essential ingredientin the act of perception, the process closely resembles an act ofinference; and, indeed, Helmholtz distinctly calls the perception ofdistance an unconscious inference or a mechanically performed act ofjudgment. I have hinted that these recovered sensations include the feelings weexperience in connection with muscular activity, as in moving our limbs, resisting or lifting heavy bodies, and walking to a distant object. Modern psychology refers the eye's instantaneous recognition of the mostimportant elements of an object (its essential or "primary" qualities)to a reinstatement of such simple experiences as these. It is, indeed, these reproductions which are supposed to constitute the substantialbackground of our percepts. Another thing worth noting with respect to this process of filling up asense-impression is that it draws on past sensations of the eye itself. Thus, when I look at the figure of an acquaintance from behind, myreproductive visual imagination supplies a representation of theimpressions I am wont to receive when the more interesting aspect of theobject, the front view, is present to my visual sense. [7] We may distinguish between different steps in the full act of visualrecognition. First of all comes the construction of a material object ofa particular figure and size, and at a particular distance; that is tosay, the recognition of a tangible thing having certain simplespace-properties, and holding a certain relation to other objects, andmore especially our own body, in space. This is the bare perception ofan object, which always takes place even in the case of perfectly newobjects, provided they are seen with any degree of distinctness. It isto be added that the reference of a sensation of light or colour to suchan object involves the inclusion of a quality answering to thesensation, as brightness, or blue colour, in the thing thus intuited. This part of the process of filling in, which is the most instantaneous, automatic, and unconscious, may be supposed to answer to the mostconstant and therefore the most deeply organized connections ofexperience; for, speaking generally, we never have an impression ofcolour, except when there are circumstances present which are fitted toyield us those simple muscular and tactual experiences through which theideas of a particular form, size, etc. , are pretty certainly obtained. The second step in this process of presentative construction is therecognition of an object as one of a class of things, for example, oranges, having certain special qualities, as a particular taste. Inthis step the connections of experience are less deeply organized, andso we are able to some extent, by reflection, to recognize it as a kindof intellectual working up of the materials supplied us by the past. Itis to be noted that this process of recognition involves a compoundoperation of classifying impressions as distinguished from that simpleoperation by which a single impression, such as a particular colour, isknown. Thus the recognition of such an object as an orange takes placeby a rapid classing of a multitude of passive sensations of colour, light, and shade, and those active or muscular sensations which aresupposed to enter into the visual perception of form. A still less automatic step in the process of visual recognition is thatof identifying individual objects, as Westminster Abbey, or a friend, John Smith. The amount of experience that is here reproduced may be verylarge, as in the case of recognizing a person with whom we have had along and intimate acquaintance. If the recognition of an object as one of a class, for example, anorange, involves a compound process of classing impressions, that of anindividual object involves a still more complicated process. Theidentification of a friend, simple as this operation may at firstappear, really takes place by a rapid classing of all the salientcharacteristic features which serve as the visible marks of thatparticular person. It is to be noted that each kind of recognition, specific andindividual, takes place by a consciousness of likeness amid unlikeness. It is obvious that a new individual object has characters not shared inby other objects previously inspected. Thus, we at once class a man witha dark-brown skin, wearing a particular garb, as a Hindoo, though he maydiffer in a host of particulars from the other Hindoos that we haveobserved. In thus instantly recognizing him as a Hindoo, we must, it isplain, attend to the points of similarity, and overlook for the instantthe points of dissimilarity. In the case of individual identification, the same thing happens. Strictly speaking, no object ever appearsexactly the same to us on two occasions. Apart from changes in theobject itself, especially in the case of living beings, there arevarying effects of illumination, of position in relation to the eye, ofdistance, and so on, which very distinctly affect the visual impressionat different times. Yet the fact of our instantly recognizing a familiarobject in spite of these fluctuations of appearance, proves that we areable to overlook a very considerable amount of diversity when a certainamount of likeness is present. It is further to be observed that in these last stages of perception weapproach the boundary line between perception and inference. Torecognize an object as one of a class is often a matter of consciousreflection and judgment, even when the class is constituted by obviousmaterial qualities which the senses may be supposed to apprehendimmediately. Still more clearly does perception pass into inference whenthe class is constituted by less obvious qualities, which require acareful and prolonged process of recollection, discrimination, andcomparison, for their recognition. Thus, to recognize a man by certainmarks of gesture and manner as a military man or a Frenchman, thoughpopularly called a perception, is much more of an unfolded process ofconscious inference. And what applies to specific recognition appliesstill more forcibly to individual recognition, which is often a matterof very delicate conscious comparison and judgment. To say where theline should be drawn here between perception and observation on the onehand, and inference on the other, is clearly impossible. Our whole studyof the illusions of perception will serve to show that the one shadesoff into the other too gradually to allow of our drawing a hard and fastline between them. Finally, it is to be noted that these last stages of perception bring usnear the boundary line which separates objective experience as commonand universal, and subjective or variable experience as confined to oneor to a few. In the bringing of the object under a certain class ofobjects there is clearly room for greater variety of individualperception. For example, the ability to recognize a man as a Frenchmanturns on a special kind of previous experience. And this transition fromthe common or universal to the individual experience is seen yet moreplainly in the case of individual recognition. To identify an object, say a particular person, commonly presupposes some previous experienceor knowledge of this object, and the existence in the past of somespecial relation of the recognizer to the recognized, if only that of anobserver. In fact, it is evident that in this mode of recognition wehave the transition from common perception to individualrecollection. [8] While we may thus distinguish different steps in the process of visualrecognition, we may make a further distinction, marking off a passiveand an active stage in the process. The one may be called the stage ofpreperception, the other that of perception proper. [9] In the first themind holds itself in a passive attitude, except in so far as theenergies of external attention are involved. The impression here awakensthe mental images which answer to past experiences according to thewell-known laws of association. The interpretative image which is totransform the impression into a percept is now being formed by a mereprocess of suggestion. When the image is thus formed, the mind may be said to enter upon a moreactive stage, in which it now views the impression through the image, orapplies this as a kind of mould or framework to the impression. Thisappears to involve an intensification of the mental image, transformingit from a representative to a presentative mental state, making itapproximate somewhat to the full intensity of the sensation. In many ofour instantaneous perceptions these two stages are indistinguishable toconsciousness. Thus, in most cases, the recognition of size, distance, etc. , takes place so rapidly that it is impossible to detect the twophases here separated. But in the classification of an object, or theidentification of an individual thing, there is often an appreciableinterval between the first reception of the impression and the finalstage of complete recognition. And here it is easy to distinguish thetwo stages of preperception and perception. The interpretative image isslowly built up by the operation of suggestion, at the close of whichthe impression is suddenly illumined as by a flash of light, and takes adefinite, precise shape. Now, it is to be noted that the process of preperception will be greatlyaided by any circumstance that facilitates the construction of theparticular interpretative image required. Thus, the more frequently asimilar process of perception has been performed in the past, the moreready will the mind be to fall into the particular way of interpretingthe impression. As G. H. Lewes well remarks, "The artist sees detailswhere to other eyes there is a vague or confused mass; the naturalistsees an animal where the ordinary eye only sees a form. " This is but oneillustration of the seemingly universal mental law, that what isrepeatedly done will be done more and more easily. The process of preperception may be shortened, not only by means of a_permanent_ disposition to frame the required interpretative scheme, theresiduum of past like processes, but also by means of any _temporary_disposition pointing in the same direction. If, for example, the mind ofa naturalist has just been occupied about a certain class of bird, thatis to say, if he has been dwelling on the _mental image_ of this bird, he will recognize one at a distance more quickly than he would otherwisehave done. Such a simple mental operation as the recognition of one ofthe less common flowers, say a particular orchid, will vary in durationaccording as we have or have not been recently forming an image of thisflower. The obvious explanation of this is that the mental image of anobject bears a very close resemblance to the corresponding percept, differing from it, indeed, in degree only, that is to say, through thefact that it involves no actual sensation. Here again we see illustrateda general psychological law, namely, that what the mind has recentlydone, it tends (within certain limits) to go on doing. It is to be noticed, further, that the perception of a single object orevent is rarely an isolated act of the mind. We recognize and understandthe things that surround us through their relations one to another. Sometimes the adjacent circumstances and events suggest a definiteexpectation of the new impression. Thus, for example, the sound of a gunheard during a walk in the country is instantly interpreted by help ofsuggestions due to the previous appearance of the sportsman, and the actof raising the gun to his shoulder. It may be added that the verbalsuggestions of others act very much like the suggestions of externalcircumstances. If I am told that a gun is going to be fired, my mind isprepared for it just as though I saw the sportsman. [10] More frequently the effect of such surrounding circumstances is to givean air of familiarity to the new impression, to shorten the interval inwhich the required interpretative image is forthcoming. Thus, whentravelling in Italy, the visual impression answering to a ruined templeor a bareheaded friar is construed much more rapidly than it would beelsewhere, because of the attitude of mind due to the surroundingcircumstances. In all such cases the process of preperception connectedwith a given impression is effected more or less completely by thesuggestions of other and related impressions. It follows from all that has been just said that our minds are never inexactly the same state of readiness with respect to a particular processof perceptional interpretation. Sometimes the meaning of an impressionflashes on us at once, and the stage of preperception becomesevanescent. At other times the same impression will fail for anappreciable interval to divulge its meaning. These differences are, nodoubt, due in part to variations in the state of attention at themoment; but they depend as well on fluctuations in the degree of themind's readiness to look at the impression in the required way. In order to complete this slight analysis of perception, we must lookfor a moment at its physical side, that is to say, at the nervousactions which are known or supposed with some degree of probability toaccompany it. The production of the sensation is known to depend on a certain externalprocess, namely, the action of some stimulus, as light, on thesense-organ, which stimulus has its point of departure in the object, such as it is conceived by physical science. The sensation arises whenthe nervous process is transmitted through the nerves to the consciouscentre, often spoken of as the sensorium, the exact seat of which isstill a matter of some debate. The intensification of the sensation by the reaction of attention issupposed to depend on some reinforcement of the nervous excitation inthe sensory centre proceeding from the motor regions, which arehypothetically regarded as the centre of attention. [11] Theclassification of the impression, again, is pretty certainly correlatedwith the physical fact that the central excitation calls into activityelements which have already been excited in the same way. The nervous counterpart of the final stage of perception, the synthesisof the sensation and the mental representation, is not clearlyascertained. A sensation clearly resembles a mental image in quality. Itis most obviously marked off from the image by its greater vividness orintensity. Agreeably to this view, it is now held by a number of eminentphysiologists and psychologists that the nervous process underlying asensation occupies the same central region as that which underlies thecorresponding image. According to this theory, the two processes differin their degree of energy only, this difference being connected with thefact that the former involves, while the latter does not involve, theperipheral region of the nervous system. Accepting this view as on thewhole well founded, I shall speak of an ideational, or rather animaginational; and a sensational nervous process, and not of anideational and a sensational centre. [12] The special force that belongs to the representative element in apercept, as compared with that of a pure "perceptional" image, [13] isprobably connected with the fact that, in the case of actual perception, the nervous process underlying the act of imaginative construction isorganically united to the initial sensational process, of which indeedit may be regarded as a continuation. For the physical counterpart of the two stages in the interpretativepart of perception, distinguished as the passive stage of preperception, and the active stage of perception proper, we may, in the absence ofcertain knowledge, fall back on the hypothesis put forward by Dr. J. Hughlings Jackson, in the articles in _Brain_ already referred to, namely, that the former answers to an action of the right hemisphere ofthe brain, the latter to a subsequent action of the left hemisphere. Theexpediting of the process of preperception in those cases where it hasfrequently been performed before, is clearly an illustration of theorganic law that every function is improved by exercise. And thetemporary disposition to perform the process due to recent imaginativeactivity, is explained at once on the physical side by the suppositionthat an actual perception and a perceptional image involve the activityof the same nervous tracts. For, assuming this to be the case, itfollows, from a well-known organic law, that a recent excitation wouldleave a temporary disposition in these particular structures to resumethat particular mode of activity. What has here been said about visual perception will apply, _mutatismutandis_, to other kinds. Although the eye is the organ of perception_par excellence_, our other senses are also avenues by which we intuitand recognize objects. Thus touch, especially when it is finelydeveloped as it is in the blind, gives an immediate knowledge ofobjects--a more immediate knowledge, indeed, of their fundamentalproperties than sight. What makes the eye so vastly superior to theorgan of touch as an instrument of perception, is first of all the rangeof its action, taking in simultaneously a large number of impressionsfrom objects at a distance as well as near; and secondly, though thismay seem paradoxical, the fact that it gives us so much indirectly, thatis, by way of association and suggestion. This is the interesting sideof visual perception, that, owing to the vast complex of distinguishablesensations of light and colour of various qualities and intensities, together with the muscular sensations attending the varying positions ofthe organ, the eye is able to recognize at any instant a whole externalworld with its fundamental properties and relations. The ear comes nextto the eye in this respect, but only after a long interval, since itssensations (even in the case of musical combinations) do notsimultaneously order themselves in an indefinitely large group ofdistinguishable elements, and since even the comparatively fewsensations which it is capable of simultaneously receiving, being altogether passive--that is to say, having no muscularaccompaniments--impart but little and vague information respecting theexternal order. It is plain, then, that in the study of illusion, wherethe indirectly known elements are the thing to be considered, the eye, and after this the ear, will mostly engage our attention. [14] So much it seemed needful to say about the mechanism of perception, inorder to understand the slight disturbances of this mechanism thatmanifest themselves in sense-illusion. It may be added that our study ofthese illusions will help still further to elucidate the exact nature ofperception. Normal mental life, as a whole, at once illustrates, and isillustrated by, abnormal. And while we need a rough provisional theoryof accurate perception in order to explain illusory perception at all, the investigation of this latter cannot fail to verify and even rendermore complete the theory which it thus temporarily adopts. _Illusions of Perception. _ With this brief psychological analysis of perception to help us, let usnow pass to the consideration of the errors incident to the process, with a view to classify them according to their psychological nature andorigin. And here there naturally arises the question, How shall we define anillusion of perception? When trying to fix the definition of illusion ingeneral, I practically disposed of this question. Nevertheless, as thepoint appears to me to be of some importance, I shall reproduce andexpand one or two of the considerations then brought forward. It is said by certain, philosophers that perception, as a whole, is anillusion, inasmuch as it involves the fiction of a real thingindependent of mind, yet somehow present to it in the act ofsense-perception. But this is a question for philosophy, not forscience. Science, including psychology, assumes that in perception thereis something real, without inquiring what it may consist of, or what itsmeaning may be. And though in the foregoing analysis of perception, viewed as a complex mental phenomenon or psychical process, I haveargued that a percept gets its concrete filling up out of elements ofconscious experience or sensations, I have been careful not to contendthat the particular elements of feeling thus represented are the_object_ of perception or the thing perceived. It may be that what wemean by a single object with its assemblage of qualities is much morethan any number of such sensations; and it must be confessed that, onthe face of it, it seems to be much more. And however this be, thequestion, What is meant by object; and is the common persuasion of theexistence of such an entity in the act of perception accurate orillusory? must be handed over to philosophy. While in the following examination of sense-illusions we put out ofsight what certain philosophers say about the illusoriness of perceptionas a whole, we shall also do well to leave out of account what physicalscience is sometimes supposed to tell us respecting a constant elementof illusion in perception. The physicist, by reducing all externalchanges to "modes of motion, " appears to leave no room in hisworld-mechanism for the secondary qualities of bodies, such as lightand heat, as popularly conceived. Yet, while allowing this, I think wemay still regard the attribution of qualities like colour to objects asin the main correct and answering to a real fact. When a person says anobject is red, he is understood by everybody as affirming somethingwhich is true or false, something therefore which either involves anexternal fact or is illusory. It would involve an external fact wheneverthe particular sensation which he receives is the result of a physicalaction (other vibrations of a certain order), which would produce a likesensation in anybody else in the same situation and endowed with thenormal retinal sensibility. On the other hand, an illusory attributionof colour would imply that there is no corresponding physical agency atwork in the case, but that the sensation is connected with exceptionalindividual conditions, as, for example, altered retinal sensibility. We are now, perhaps, in a position to frame a rough definition of anillusion of perception as popularly understood. A large number of suchphenomena may be described as consisting in the formation of percepts orquasi-percepts in the minds of individuals under external circumstanceswhich would not give rise to similar percepts in the case of otherpeople. A little consideration, however, will show that this is not an adequatedefinition of what is ordinarily understood by an illusion of sense. There are special circumstances which are fitted to excite a momentaryillusion in all minds. The optical illusions due to the reflection andrefraction of light are not peculiar to the individual, but arise in allminds under precisely similar external conditions. It is plain that the illusoriness of a perception is in these casesdetermined in relation to the sense-impressions of other moments andsituations, or to what are presumably better percepts than the presentone. Sometimes this involves an appeal from one sense to another. Thus, there is the process of verification of sight by touch, for example, inthe case of optical images, a mode of perception which, as we have seen, gives a more direct cognition of external quality. Conversely, there mayoccasionally be a reference from touch to sight, when it is a questionof discriminating two points lying very close to one another. Finally, the same sense may correct itself, as when the illusion of thestereoscope is corrected by afterwards looking at the two separatepictures. We may thus roughly define an illusion of perception as consisting inthe formation of a quasi-percept which is peculiar to an individual, orwhich is contradicted by another and presumably more accurate percept. Or, if we take the meaning of the word common to include both theuniversal as contrasted with the individual experience, and thepermanent, constant, or average, as distinguished from the momentary andvariable percept, we may still briefly describe an illusion ofperception as a deviation from the common or collective experience. _Sources of Sense-Illusion. _ Understanding sense-illusion in this way, let us glance back at theprocess of perception in its several stages or aspects, with the objectof discovering what room occurs for illusion. It appears at first as if the preliminary stages--the reception, discrimination, and classification of an impression--would not offer theslightest opening for error. This part of the mechanism of perceptionseems to work so regularly and so smoothly that one can hardly conceivea fault in the process. Nevertheless, a little consideration will showthat even here all does not go on with unerring precision. Let us suppose that the very first step is wanting--distinct attentionto an impression. It is easy to see that this will favour illusion byleading to a confusion of the impression. Thus the timid man will morereadily fall into the illusion of ghost-seeing than a cool-headedobservant man, because he is less attentive to the actual impression ofthe moment. This inattention to the sense-impression will be found to bea great co-operating factor in the production of illusions. But if the sensation is properly attended to, can there be error througha misapprehension of what is actually in the mind at the moment? To saythat there can may sound paradoxical, and yet in a sense this isdemonstrable. I do not mean that there is an observant mind behind anddistinct from the sensation, and failing to observe it accuratelythrough a kind of mental short-sightedness. What I mean is that theusual psychical effect of the incoming nervous process may to someextent be counteracted by a powerful reaction of the centres. In thecourse of our study of illusions, we shall learn that it is possible forthe quality of an impression, as, for example, of a sensation of colour, to be appreciably modified when there is a strong tendency to regard itin one particular way. Postponing the consideration of these, we may say that certain illusionsappear clearly to take their start from an error in the process ofclassifying or identifying a present impression. On the physical side, we may say that the first stages of the nervous process, the dueexcitation of the sensory centre in accordance with the form of theincoming stimulation and the central reaction involved in therecognition of the sensation, are incomplete. These are so limited andcomparatively unimportant a class, that it will be well to dispose ofthem at once. _Confusion of the Sense-Impression. _ The most interesting case of such an error is where the impression isunfamiliar and novel in character. I have already remarked that in themental life of the adult perfectly new sensations never occur. At thesame time, comparatively novel impressions sometimes arise. Parts of thesensitive surface of the body which rarely undergo stimulation aresometimes acted on, and at other times they receive partially new modesof stimulation. In such cases it is plain that the process of classingthe sensation or recognizing it is not completed. It is found thatwhenever this happens there is a tendency to exaggerate the intensity ofthe sensation. The very fact of unfamiliarity seems to give to thesensation a certain exciting character. As something new and strange, itfor the instant slightly agitates and discomposes the mind. Being unableto classify it with its like, we naturally magnify its intensity, andso tend to ascribe it to a disproportionately large cause. For instance, a light bandage worn about the body at a part usually freefrom pressure is liable to be conceived as a weighty mass. The odd senseof a big cavity in the mouth, which we experience just after the loss ofa tooth, is probably another illustration of this principle. And a thirdexample may also be supplied from the recollection of the dentist'spatient, namely, the absurd imagination which he tends to form as towhat is actually going on in his mouth when a tooth is being bored by amodern rotating drill. It may be found that the same principle helps toaccount for the exaggerated importance which we attach to theimpressions of our dreams. It is evident that all indistinct impressions are liable to be wronglyclassed. Sensations answering to a given colour or form, are, whenfaint, easily confused with other sensations, and so an opening occursfor illusion. Thus, the impressions received from distant objects arefrequently misinterpreted, and, as we shall see by-and-by, it is in thisregion of hazy impression that imagination is wont to play its moststartling pranks. It is to be observed that the illusions arising from wrongclassification will be more frequent in the case of those senses wherediscrimination is low. Thus, it is much easier in a general way toconfuse two sensations of smell than two sensations of colour. Hence thegreat source of such errors is to be found in that mass of obscuresensation which is connected with the organic processes, as digestion, respiration, etc. , together with those varying tactual and motorfeelings, which result from what is called the subjective stimulation ofthe tactual nerves, and from changes in the position and condition ofthe muscles. Lying commonly in what is known as the sub-conscious regionof mind, undiscriminated, vague, and ill-defined, these sensations, whenthey come to be specially attended to, readily get misapprehended, andso lead to illusion, both in waking life and in sleep. I shall haveoccasion to illustrate this later on. With these sensations, the result of stimulations coming from remoteparts of the organism, may be classed the ocular impressions which wereceive in indirect vision. When the eye is not fixed on an object, theimpression, involving the activity of some-peripheral region of theretina, is comparatively indistinct. This will be much more the casewhen the object lies at a distance for which the eye is not at the timeaccommodated. And in these circumstances, when we happen to turn ourattention to the impression, we easily misapprehend it, and so fall intoillusion. Thus, it has been remarked by Sir David Brewster, in his_Letters on Natural Magic_ (letter vii. ), that when looking through awindow at some object beyond, we easily suppose a fly on the window-paneto be a larger object, as a bird, at a greater distance. [15] While these cases of a confusion or a wrong classification of thesensation are pretty well made out, there are other illusions orquasi-illusions respecting which it is doubtful whether they should bebrought under this head. For example, it was found by Weber, that whenthe legs of a pair of compasses are at a certain small distance apartthey will be felt as two by some parts of the tactual surface of thebody, but only as one by other parts. How are we to regard thisdiscrepancy? Must we say that in the latter case there are twosensations, only that, being so similar, they are confused one withanother? There seems some reason for so doing, in the fact that, by arepeated exercise of attention to the experiment, they may afterwards berecognized as two. We here come on the puzzling question, How much in the character of thesensation must be regarded as the necessary result of the particularmode of nervous stimulation at the moment, together with the laws ofsensibility, and how much must be put down to the reaction of the mindin the shape of attention and discrimination? For our present purpose wemay say that, whenever a deliberate effort of attention does not sufficeto alter the character of a sensation, this may be pretty safelyregarded as a net result of the nervous process, and any error arisingmay be referred to the later stages of the process of perception. Thus, for example, the taking of the two points of a pair of compasses forone, where the closest attention does not discover the error, is bestregarded as arising, not from a confusion of the sense-impression, butfrom a wrong interpretation of a sensation, occasioned by anoverlooking of the limits of local discriminative sensibility. _Misinterpretation of the Sense-Impression. _ Enough has been said, perhaps, about those errors of perception whichhave their root in the initial process of sensation. We may now pass tothe far more important class of illusions which are related to the laterstages of perception, that is to say, the process of interpreting thesense-impression. Speaking generally, one may describe an illusion ofperception as a misinterpretation. The wrong kind of interpretativemental image gets combined with the impression, or, if with Helmholtz weregard perception as a process of "unconscious inference, " we may saythat these illusions involve an unconscious fallacious conclusion. Or, looking at the physical side of the operation, it may be said that thecentral course taken by the nervous process does not correspond to theexternal relations of the moment. As soon as we inspect these illusions of interpretation, we see thatthey fall into two divisions, according as they are connected with theprocess of _suggestion_, that is to say, the formation of theinterpretative image so far as determined by links of association withthe actual impression, or with an independent process of _preperception_as explained above. Thus, for example, we fall into the illusion ofhearing two voices when our shout is echoed back, just because thesecond auditory impression irresistibly calls up the image of a secondshouter. On the other hand, a man experiences the illusion of seeingspectres of familiar objects just after exciting his imagination over aghost-story, because the mind is strongly predisposed to frame this kindof percept. The first class of illusions arises from without, thesense-impression being the starting-point, and the process ofpreperception being controlled by this. The second class arises ratherfrom within, from an independent or spontaneous activity of theimagination. In the one case the mind is comparatively passive; in theother it is active, energetically reacting on the impression, andimpatiently anticipating the result of the normal process ofpreperception. Hence I shall, for brevity's sake, commonly speak of themas Passive and Active Illusions. [16] I may, perhaps, illustrate these two classes of illusion by the simileof an interpreter poring over an old manuscript. The first would be dueto some peculiarity in the document misleading his judgment, the secondto some caprice or preconceived notion in the interpreter's mind. It is not difficult to define conjecturally the physiological conditionsof these two large classes of illusion. On the physical side, anillusion of sense, like a just perception, is the result of a fusion ofthe nervous process answering to a sensation with a nervous processanswering to a mental image. In the case of passive illusions, thisfusion may be said to take place in consequence of some point ofconnection between the two. The existence of such a connection appearsto be involved in the very fact of suggestion, and may be said to bethe organic result of frequent conjunctions of the two parts of thenervous operation in our past history. In the case of active illusions, however, which spring rather from the independent energy of a particularmode of the imagination, this point of organic connection is not theonly or even the main thing. In many cases, as we shall see, there isonly a faint shade of resemblance between the present impression and themental image with which it is overlaid. The illusions dependent onvivid, expectation thus answer much less to an objective conjunction ofpast experiences than to a capricious subjective conjunction of mentalimages. Here, then, the fusion of nervous processes must have anothercause. And it is not difficult to assign such a cause. The antecedentactivity of imagination doubtless involves as its organic result apowerful temporary disposition in the nervous structures concerned to goon acting. In other words, they remain in a state of sub-excitation, which can be raised to full excitation by a slight additional force. Themore powerful this disposition in the centres involved in the act ofimagination, the less the additional force of external stimulus requiredto excite them to full activity. Considering the first division, passive illusions, a little further, weshall see that they may be broken up into two sub-classes, according tothe causes of the errors. In a general way we assume that the impressionalways answers to some quality of the object which is perceived, andvaries with this; that, for example, our sensation of colour invariablyrepresents the quality of external colour which we attribute to theobject. Or, to express it physically, we assume that the external forceacting on the sense-organ invariably produces the same effect, and thatthe effect always varies with the external cause. But this assumption, though true in the main, is not perfectly correct. It supposes that theorganic conditions are constant, and that the organic process faithfullyreflects the external operation. Neither of these suppositions isstrictly true. Although in general we may abstract from the organism andview the relation between the external fact and the mental impression asdirect, we cannot always do so. This being so, it is possible for errors of perception to arise throughpeculiarities of the nervous organization itself. Thus, as I have justobserved, sensibility has its limits, and these limits are thestarting-point in a certain class of widely shared or _common_illusions. An example of this variety is the taking of the two points ofa pair of compasses for one by the hand, already referred to. Again, thecondition of the nervous structures varies indefinitely, so that one andthe same stimulus may, in the case of two individuals, or of the sameindividual at different times, produce widely unlike modes of sensation. Such variations are clearly fitted to lead to gross _individual_ errorsas to the external cause of the sensation. Of this sort is the illusorysense of temperature which we often experience through a special stateof the organ employed. While there are these errors of interpretation due to some peculiarityof the organization, there are others which involve no such peculiarity, but arise through the special character or exceptional conformation ofthe environment at the moment. Of this order are the illusions connectedwith the reflection of light and sound. We may, perhaps, distinguish thefirst sub-class as organically conditioned illusions, and the second asextra-organically determined illusions. It may be added that the latterare roughly describable as common illusions. They thus answer in ameasure to the first variety of organically conditioned illusions, namely, those connected with the limits of sensibility. On the otherhand, the active illusions, being essentially individual or subjective, may be said to correspond to the other variety of this class--thoseconnected with variations of sensibility. Our scheme of sense-illusions is now complete. First of all, we shalltake up the passive illusions, beginning with those which areconditioned by special circumstances in the organism. After that weshall illustrate those which depend on peculiar circumstances in theenvironment. And finally, we shall separately consider what I havecalled the active illusions of sense. It is to be observed that these illusions of perception properly socalled, namely, the errors arising from a wrong interpretation of animpression, and, not from a confusion of one impression with another arechiefly illustrated in the region of the two higher senses, sight andhearing. For it is here, as we have seen, that the interpretativeimagination has most work to do in evolving complete percepts ofmaterial, tangible objects, having certain relations in space, out of alimited and homogeneous class of sensations, namely, those of light andcolour, and of sound. As I have before observed, tactual perception, inso far as it is the recognition of an object of a certain size, hardness, and distance from our body, involves the least degree ofinterpretation, and so offers little room for error; it is only whentactual perception amounts to the _recognition_ of an individual object, clothed with secondary as well as primary qualities, that an opening forpalpable error occurs. With respect, however, to the first sub-class of these illusions, namely, those arising from organic peculiarities which give a twist, soto speak, to the sensation, no very marked contrast between thedifferent senses presents itself. So that in illustrating this group weshall be pretty equally concerned with the various modes of perceptionconnected with the different senses. It may be said once for all that in thus marking off from one anothercertain groups of illusion, I am not unmindful of the fact that thesedivisions answer to no very sharp natural distinctions. In fact, it willbe found that one class gradually passes into the other, and that thedifferent characteristics here separated often combine in a mostperplexing way. All that is claimed for this classification is that itis a convenient mode of mapping out the subject. CHAPTER IV. ILLUSIONS OF PERCEPTION--_continued_. A. _Passive Illusions (a) as determined by the Organism. _ In dealing with the illusions which are related to certain peculiaritiesin the nervous organism and the laws of sensibility, I shall commencewith those which are connected with certain limits of sensibility. _Limits of Sensibility. _ To begin with, it is known that the sensation does not always answer tothe external stimulus in its degree or intensity. Thus, a certain amountof stimulation is necessary before any sensation arises. And this will, of course, be greater when there is little or no attention directed tothe impression, that is to say, no co-operating central reaction. Thusit happens that slight stimuli go overlooked, and here illusion may haveits starting-point. The most familiar example of such slight errors isthat of movement. When we are looking at objects, our ocular muscles areapt to execute very slight movements which escape our notice. Hence wetend, under certain circumstances, to carry over the retinal result ofthe movement, that is to say, the impression produced by a shifting ofthe parts of the retinal image to new nervous elements, to the objectitself, and so to transform a "subjective" into an "objective" movement. In a very interesting work on apparent or illusory movements, ProfessorHoppe has fully investigated the facts of such slight movements, andendeavoured to specify their causes. [17] Again, even when the stimulus is sufficient to produce a consciousimpression, the degree of the feeling may not represent the degree ofthe stimulus. To take a very inconspicuous case, it is found by Fechnerthat a given increase of force in the stimulus produces a less amount ofdifference in the resulting sensations when the original stimulus is apowerful one than when it is a feeble one. It follows from this, thatdifferences in the degree of our sensations do not exactly correspond toobjective differences. For example, we tend to magnify the differencesof light among objects, all of which are feebly illuminated, that is tosay, to see them much more removed from one another in point ofbrightness than when they are more strongly illuminated. Helmholtzrelates that, owing to this tendency, he has occasionally caughthimself, on a dark night, entertaining the illusion that thecomparatively bright objects visible in twilight were self-luminous. [18] Again, there are limits to the conscious separation of sensations whichare received together, and this fact gives rise to illusion. In general, the number of distinguishable sensations answers to the number ofexternal causes; but this is not always the case, and here we naturallyfall into the error of mistaking the number of the stimuli. Referencehas already been made to this fact in connection with the questionwhether consciousness can be mistaken as to the character of a presentfeeling. The case of confusing two impressions when the sensory fibres involvedare very near one another, has already been alluded to. Both in touchand in sight we always take two or more points for one when they areonly separated by an interval that falls below the limits of localdiscrimination. It seems to follow from this that our perception of theworld as a continuum, made up of points perfectly continuous one withanother may, for what we know, be illusory. Supposing the universe toconsist of atoms separated by very fine intervals, then it isdemonstrable that it would appear to our sensibility as a continuum, just as it does now. [19] Two or more simultaneous sensations are indistinguishable from oneanother, not only when they have nearly the same local origin, but underother circumstances. The blending of partial sensations of tone in a_klang_-sensation, and the coalescence in certain cases of theimpressions received by way of the two retinas, are examples of this. Itis not quite certain what determines this fusion of two simultaneousfeelings. It may be said generally that it is favoured by similaritybetween the sensations;[20] by a comparative feebleness of one of thefeelings; by the fact of habitual concomitance, the two sensationsoccurring rarely, if ever, in isolation; and by the presence of a mentaldisposition to view them as answering to one external object. Theseconsiderations help us to explain the coalescence of the retinalimpressions and its limits, the fusion of partial tones, and so on. [21] It is plain that this fusion of sensations, whatever its exactconditions may be, gives rise to error or wrong interpretation of thesense-impression. Thus, to take the points of two legs of a pair ofcompasses for one point is clearly an illusion of perception. Here isanother and less familiar example. Very cold and smooth surfaces, asthose of metal, often appear to be wet. I never feel sure, after wipingthe blades of my skates, that they are perfectly dry, since they alwaysseem more or less damp to my hand. What is the reason of this? Helmholtzexplains the phenomenon by saying that the feeling we call by the nameof wetness is a compound sensation consisting of one of temperature andone of touch proper. These sensations occurring together so frequently, blend into one, and so we infer, according to the general instinctivetendency already noticed, that there is one specific quality answeringto the feeling. And since the feeling is nearly always produced bysurfaces moistened by cold liquid, we refer it to this circumstance, andspeak of it as a feeling of wetness. Hence, when the particularconjunction of sensations arises apart from this external circumstance, we erroneously infer its presence. [22] The most interesting case of illusion connected with the fusion ofsimultaneous sensations, is that of single vision, or the deeplyorganized habit of combining the sensations of what are called thecorresponding points of the two retinas. This coalescence of twosensations is so far erroneous since it makes us overlook the existenceof two distinct external agencies acting on different parts of thesensitive surface of the body. And this is the more striking in the caseof looking at solid objects, since here it is demonstrable that theforces acting on the two retinas are not perfectly similar. Nevertheless, such a coalescence plainly answers to the fact that theseexternal agencies usually arise in one and the same object, and thisunity of the object is, of course, the all-important thing to be sureof. This habit may, however, beget palpable illusion in another way. Incertain exceptional cases the coalescence does not take place, as when Ilook at a distant object and hold a pencil just before my eyes. [23] Andin this case the organized tendency to take one visual impression forone object asserts its force, and I tend to fall into the illusion ofseeing two separate pencils. If I do not wholly lapse into the error, itis because my experience has made me vaguely aware that double imagesunder these circumstances answer to one object, and that if there werereally two pencils present I should have four visual impressions. Once more, it is a law of sensory stimulation that an impressionpersists for an appreciable time after the cessation of the action ofthe stimulus. This "after sensation" will clearly lead to illusion, inso far as we tend to think of the stimulus as still at work. It forms, indeed, as will be seen by-and-by, the simplest and lowest stage ofhallucination. Sometimes this becomes the first stage of a palpableerror. After listening to a child crying for some time the ear easilydeceives itself into supposing that the noise is continued when it hasactually ceased. Again, after taking a bandage from a finger, thetingling and other sensations due to the pressure sometimes persist fora good time, in which case they easily give rise to an illusion that thefinger is still bound. It follows from this fact of the reverberation of the nervous structuresafter the removal of a stimulus, that whenever two discontinuousstimulations follow one another rapidly enough, they will appearcontinuous. This fact is a fruitful source of optical illusion. Theappearance of a blending of the stripes of colours on a rotating disc ortop, of the formation of a ring of light by swinging round a piece ofburning wood, and the illusion of the toy known as the thaumatrope, orwheel of life, all depend on this persistence of retinal impression. Many of the startling effects of sleight of hand are undoubtedly due inpart to this principle. If two successive actions or sets ofcircumstances to which the attention of the spectator is speciallydirected follow one another by a very narrow interval of time, theyeasily appear continuous, so that there seems absolutely no time for theintroduction of an intermediate step. [24] There is another limit to sensibility which is in a manner the oppositeto the one just named. It is a law of nervous stimulation that acontinued activity of any structure results in less and less psychicresult, and that when a stimulus is always at work it ceases in time tohave any appreciable effect. The common illustration of this law isdrawn from the region of sound. A constant noise, as of a mill, ceasesto produce any conscious sensation. This fact, it is plain, may easilybecome the commencement of an illusion. Not only may we mistake ameasure of noise for perfect silence, [25] we may misconceive the realnature of external circumstances by overlooking some continuousimpression. Curious illustrations of this effect are found in optical illusions, namely, the errors we make respecting the movement of stationary objectsafter continued movement of the eyes. When, for example, in a railwaycarriage we have for some time been following the (apparent) movement ofobjects, as trees, etc. , and turn our eyes to an apparently stationaryobject, as the carpet of the compartment, this seems to move in thecontrary direction to that of the trees. Helmholtz's explanation of thisillusion is that when we suppose that we are fixing our eye on thecarpet we are really continuing to move it over the surface by reason ofthe organic tendency, already spoken of, to go on doing anything thathas been done. But since we are unaware of this prolonged series ofocular movements, the muscular feelings having become faint, we take theimpression produced by the sliding of the picture over the retina to bethe result of a movement of the object. [26] Another limit to our sensibility, which needs to be just touched onhere, is known by the name of the specific energy of the nerves. One andthe same nerve-fibre always reacts in a precisely similar way, whateverthe nature of the stimulus. Thus, when the optic nerve is stimulated inany manner, whether by light, mechanical pressure, or an electriccurrent, the same effect, a sensation of light, follows. [27] In a usualway, a given class of nerve-fibre is only stimulated by one kind ofstimulus. Thus, the retina, in ordinary circumstances, is stimulated bylight. Owing to this fact, there has arisen a deeply organized habit oftranslating the impression in one particular way. Thus, I instinctivelyregard a sensation received by means of the optic nerve as one caused bylight. Accordingly, whenever circumstances arise in which a like sensation isproduced by another kind of stimulus, we fall into illusion. Thephosphenes, or circles of light which are seen when the hinder part ofthe eyeball is pressed, may be said to be illusory in so far as wespeak of them as perceptions of light, thus referring them to theexternal physical agency which usually causes them. The same remarkapplies to those "subjective sensations, " as they are called, which areknown to have as their physical cause subjective stimuli, consisting, inthe case of sight, in varying conditions of the peripheral organ, asincreased blood-pressure. Strictly speaking, such simple feelings asthese appear to be, involve an ingredient of false perception: in sayingthat we _perceive_ light at all, we go beyond the pure sensation, interpreting this wrongly. Very closely connected with this limitation of our sensibility isanother which refers to the consciousness of the local seat, or originof the impression. This has so far its basis in the sensation itself asit is well known that (within the limits of local discrimination, referred to above) sensations have a particular "local" colour, whichvaries in the case of each of the nervous fibres by the stimulation ofwhich they arise. [28] But though this much is known through a differencein the sensibility, nothing more is known. Nothing can certainly beascertained by a mere inspection of the sensation as to the distance thenervous process has travelled, whether from the peripheral terminationof the fibre or from some intermediate point. In a general way, we refer our sensations to the peripheral endings ofthe nerves concerned, according to what physiologists have called "thelaw of eccentricity. " Thus I am said to feel the pain caused by abruise in the foot in the member itself. This applies also to some ofthe sensations of the special senses. Thus, impressions of taste areclearly localized in the corresponding peripheral terminations. With respect to the sense of smell, and still more to those of hearingand sight, where the impression is usually caused by an object at adistance from the peripheral organ, our attention to this external causeleads us to overlook in part the "bodily seat" of the sensation. Yeteven here we are dimly aware that the sensation is received by way of aparticular part of the sensitive surface, that is to say, by aparticular sense-organ. Thus, though referring an odour to a distantflower, we perceive that the sensation of odour has its bodily origin inthe nose. And even in the case of hearing and sight, we vaguely referthe impressions, as such, to the appropriate sense-organ. There is, indeed, in these cases a double local reference, a faint one to theperipheral organ which is acted on, and a more distinct one to theobject or the force in the environment which acts on this. Now, it may be said that the act of localization is in itself distinctlyillusory, since it is known that the sensation first arises inconnection with the excitation of the sensory _centre_, and not of theperipheral fibre. [29] Yet it must at least be allowed that thislocalization of sensation answers to the important fact that, underusual circumstances, the agency producing the sensation is applied atthis particular point of the organism, the knowledge of which point issupposed by modern psychologists to have been very slowly learnt by theindividual and the race, through countless experiments with the movingorgan of touch, assisted by the eye. Similarly, the reference of the impression, in the case of hearing andsight, to an object in the environment, though, as we have seen, fromone point of view illusory, clearly answers to a fact of our habitualexperience; for in an immense preponderance of cases at least a visualor auditory impression does arise through the action on the sense-organof a force (ether or air waves) proceeding from a distant object. In some circumstances, however, even this element of practical truthdisappears, and the localization of the impression, both within andwithout the organism, becomes altogether illusory. This result isinvolved in the illusions, already spoken of, which arise from theinstinctive tendency to refer sensations to the ordinary kind ofstimulus. Thus, when a feeling resulting from a disturbance in the opticnerve is interpreted as one of external light vaguely felt to be actingon the eye, or one resulting from some action set up in the auditoryfibre as a sensation of external sound vaguely felt to be entering theear, we see that the error of localization is a consequence of the othererror already characterized. As I have already observed, an excitation of a nerve at any other pointthan the peripheral termination, occurs but rarely in normal life. Onefamiliar instance is the stimulation of the nerve running to the handand fingers, by a sharp blow on the elbow over which it passes. Aseverybody knows, this gives rise to a sense of pain at the _extremities_of the nerve. The most common illustration of such errors oflocalization is found in subjective sensations, such as the impressionwe sometimes have of something creeping over the skin, of a disagreeabletaste in the mouth, of luminous spots floating across the field ofvision, and so on. The exact physiological seat of these is often amatter of conjecture only; yet it may safely be said that in manyinstances the nervous excitation originates at some point considerablyshort of its peripheral extremity: in which case there occurs theillusion of referring the impressions to the peripheral sense-organ, andto an external force acting on this. The most striking instances of these errors of localization are found inabnormal circumstances. It is well known that a man who has lost a legrefers all sensations arising from a stimulation of the truncated fibresto his lost foot, and in some cases has even to convince himself of thenon-existence of his lost member by sight or touch. Patients oftendescribe these experiences in very odd language. "If, " says one of Dr. Weir Mitchell's patients, "I should say I am more sure of the leg whichain't than the one which air, I guess I should be about correct. "[30] There is good reason for supposing that this source of error plays aprominent part in the illusions of the insane. Diseased centres may beaccompanied by disordered peripheral structures, and so subjectivesensation may frequently be the starting-point of the wildest illusions. Thus, a patient's horror of poison may have its first origin in somesubjective gustatory sensation. Similarly, subjective tactual sensationsmay give rise to gross illusions, as when a patient "feels" his bodyattacked by foul and destructive creatures. It may be well to remark that this mistaken interpretation of the seator origin of subjective sensation is closely related to hallucination. In so far as the error involves the ascription of the sensation to aforce external to the sense-organ, this part of the mental process must, when there is no such force present, be viewed as hallucinatory. Thus, the feeling of something creeping over the skin is an hallucination inthe sense that it implies the idea of an object external to the skin. Similarly, the projection of an ocular impression due to retinaldisturbance into the external field of vision, may rightly be named anhallucination. But the case is not always so clear as this. Thus, forexample, when a gustatory sensation is the result of an alteredcondition of the saliva, it may be said that the error is as much anillusion as an hallucination. [31] In a wide sense, again, all errors connected with those subjectivesensations which arise from a stimulation of the peripheral regions ofthe nerve may be called illusions rather than hallucinations. Or, ifthey must be called hallucinations, they may be distinguished as"peripheral" from those "central" hallucinations which arise through aninternal automatic excitation of the sensory centre. It is plain fromthis that the region of subjective sensation is an ambiguous region, where illusion and hallucination mix and become confused. To this pointI shall have occasion to return by-and-by. I have now probably said enough respecting the illusions that arisethrough the fact of there being fixed limits to our sensibility. The_rationale_ of these illusions is that whenever the limit is reached, wetend to ignore it and to interpret the impression in the customary way. _Variations of Sensibility. _ We will now pass to a number of illusions which depend on somethingvariable in the condition of our sensibility, or some more or lessexceptional organic circumstance. These variations may be momentary andtransient or comparatively permanent. The illusion arises in each casefrom our ignoring the variation, and treating a given sensation underall circumstances as answering to one objective cause. First of all, the variation of organic state may affect our mentalrepresentation of the strength of the stimulus or external cause. Herethe fluctuation may be a temporary or a permanent one. The first case isillustrated in the familiar example of taking a room to be brighterthan it is when emerging from a dark one. Another striking example isthat of our sense of the temperature of objects, which is known to bestrictly relative to a previous sensation, or more correctly to themomentary condition of the organ. Yet, though every intelligent personknows this, the deeply rooted habit of making sensation the measure ofobjective quality asserts its sway, and frequently leads us intoillusion. The well-known experiment of first plunging one hand in coldwater, the other in hot, and then dipping them both in tepid, is astartling example of this organized tendency. For here we are stronglydisposed to accept the palpable contradiction that the same water is atonce warm and cool. Far more important than these temporary fluctuations of sensibility arethe permanent alterations. Excessive fatigue, want of proper nutrition, and certain poisons are well known to be causes of such changes. Theyappear most commonly under two forms, exalted sensibility, orhyperæsthesia, and depressed sensibility, or anæsthesia. In theseconditions flagrant errors are made as to the real magnitude of thecauses of the sensations. These variations may occur in normal life tosome extent. In fairly good health we experience at times strangeexaltations of tactual sensibility, so that a very slight stimulus, suchas the contact of the bed-clothes, becomes greatly exaggerated. In diseased states of the nervous system these variations of sensibilitybecome much more striking. The patient who has hyperæsthesia fears totouch a perfectly smooth surface, or he takes a knock at the door to bea clap of thunder. The hypochondriac may, through an increase oforganic sensibility, translate organic sensations as the effect of someliving creature gnawing at his vitals. Again, states of anæsthesia leadto odd illusions among the insane. The common supposition that the bodyis dead, or made of wood or of glass, is clearly referable in part tolowered sensibility of the organism. [32] It is worth adding, perhaps, that these variations in sensibility giverise not only to sensory but also to motor illusions. To take a homelyinstance, the last miles of a long walk seem much longer than the first, not only because the sense of fatigue leading us to dwell on thetransition of time tends to magnify the apparent duration, but becausethe fatigued muscles and connected nerves yield a new set of sensationswhich constitute an exaggerated standard of measurement. A number ofoptical illusions illustrate the same thing. Our visual sense ofdirection is determined in part by the feelings accompanying the actionof the ocular muscles, and so is closely connected with the perceptionof movement, which has already been touched on. If an ocular muscle ispartially paralyzed it takes a much greater "effort" to effect a givenextent of movement than when the muscle is sound. Hence any movementperformed by the eye seems exaggerated. Hence, too, in this conditionobjects are seen in a wrong direction; for the patient reasons that theyare where they would seem to be if he had executed a wider movement thanhe really has. This may easily be proved by asking him to try to seizethe object with, his hand. The effect is exaggerated when completeparalysis sets in, and no actual movement occurs in obedience to theimpulse from within. [33] Variations in the condition of the nerve affect not only the degree, butalso the quality of the sensation, and this fact gives rise to a newkind of illusion. The curious phenomena of colour-contrast illustratemomentary alterations of sensibility. When, after looking at a greencolour for a time, I turn my eye to a grey surface and see this of thecomplementary rose-red hue, the effect is supposed to be due to atemporary fatigue of the retina in relation to those ingredients of thetotal light in the second case which answer to the partial light in thefirst (the green rays). [34] These momentary modifications of sensibility are of no practicalsignificance, being almost instantly corrected. Other modifications aremore permanent. It was found by Himly that when the retina isoverexcitable every stimulus is raised in the spectrum scale of colours. Thus, violet becomes red. An exactly opposite effect is observed whenthe retina is torpid. [35] Certain poisons are known to affect thequality of the colour-impression. Thus, santonin, when taken in anyquantity, makes all colourless objects look yellow. Severe pathologicaldisturbances are known to involve, in addition to hyperæsthesia andanæsthesia, what, has been called paræsthesia, that is to say, thatcondition in which the quality of sensation is greatly changed. Thus, for example, to one in this state all food appears to have a metallictaste, and so on. If we now glance back at the various groups of illusions justillustrated, we find that they all have this feature in common: theydepend on the general mental law that when we have to do with theunfrequent, the unimportant, and therefore unattended to, and theexceptional, we employ the ordinary, the familiar, and the well-known asour standard. Thus, whether we are dealing with sensations that fallbelow the ordinary limits of our mental experience, or with those whicharise in some exceptional state of the organism, we carry the habitsformed in the much wider region of average every-day perception with us. In a word, illusion in these cases always arises through what may, figuratively at least, be described as the application of a rule, validfor the majority of cases, to an exceptional case. In the varieties of illusion just considered, the circumstance thatgives the peculiarity to the case thus wrongly interpreted has beenreferred to the organism. In the illusions to which we now pass, it willbe referred to the environment. At the same time, it is plain that thereis no very sharp distinction between the two classes. Thus, the visualillusion produced by pressing the eyeball might be regarded not only asthe result of the organic law of the "specific energy" of the nerves, but, with almost equal appropriateness, as the consequence of anexceptional state of things in the environment, namely, the pressure ofa body on the retina. As I have already observed, the classificationhere adopted is to be viewed simply as a rough expedient for securingsomething like a systematic review of the phenomena. CHAPTER V. ILLUSIONS OF PERCEPTION--_continued_. A. _Passive Illusions (b) as determined by the Environment. _ In the following groups of illusion we may look away from nervousprocesses and organic disturbances, regarding the effect of any externalstimulus as characteristic, that is, as clearly marked off from theeffects of other stimuli, and as constant for the same stimulus. Thesource of the illusion will be looked for in something exceptional inthe external circumstances, whereby one object or condition of an objectimitates the effect of another object or condition, to which, owing to alarge preponderance of experience, we at once refer it. _Exceptional Relation of Stimulus to Organ. _ A transition from the preceding to the following class of illusions isto be met with in those errors which arise from a very exceptionalrelation between the stimulus and the organ of sense. Such a state ofthings is naturally interpreted by help of more common and familiarrelations, and so error arises. For example, we may grossly misinterpret the intensity of a stimulusunder certain circumstances. Thus, when a man crunches a biscuit, he hasan uncomfortable feeling that the noise as of all the structures of hishead being violently smashed is the same to other ears, and he may evenact on his illusory perception, by keeping at a respectful distance fromall observers. And even though he be a physiologist, and knows that theforce of sensation in this case is due to the propagation of vibrationsto the auditory centre by other channels than the usual one of the ear, the deeply organized impulse to measure the strength of an externalstimulus by the intensity of the sensation asserts its force. Again, if we turn to the process of perceptional construction properlyso called, the reference of the sensation to a material object lying ina certain direction, etc. , we find a similar transitional form ofillusion. The most interesting case of this in visual perception is thatof a disturbance or displacement of the organ by external force. Forexample, an illusory sense of direction arises by the simple action ofclosing one eye, say the left, and pressing the other eyeball with oneof the fingers a little outwards, that is to the right. The result ofthis movement is, of course, to transfer the retinal picture to newnervous elements further to the right. And since, in this instance, thedisplacement is not produced in the ordinary way by the activity of theocular muscle making itself known by certain feelings of movement, it isdisregarded altogether, and the direction of the objects is judged asthough the eye were stationary. A somewhat similar illusion as to direction occurs in auditoryperception. The sense of direction by the ear is known to be due in partto the action of the auricle, or projecting part of the ear. Thiscollects the air-waves, and so adds to the intensity of the sounds, especially those coming from in front, and thus assists in theestimation of direction. This being so, if an artificial auricle isplaced in front of the ears; if, for example, the two hands are eachbent into a sort of auricle, and placed in front of the ears, the backof the hand being in front, the sense of direction (as well as ofdistance) is confused. Thus, sounds really travelling from a point infront of the head will appear to come from behind it. Again, the perception of the unity of an object is liable to befalsified by the introduction of exceptional circumstances into thesense-organ. This is illustrated in the well-known experiment ofcrossing two fingers, say the third and fourth, and placing a marble orother small round object between them. Under ordinary circumstances, thetwo lateral surfaces (that is, the outer surfaces of the two fingers)now pressed by the marble, can only be acted on simultaneously by _two_objects having convex surfaces. Consequently, we cannot help feeling thepresence of two objects in this exceptional instance. The illusion isanalogous to that of the stereoscope, to be spoken of presently. _Exceptional External Arrangements. _ Passing now to those cases where the exceptional circumstance isaltogether exterior to the organ, we find a familiar example in theillusions connected with the action of well-known physical forces, asthe refraction of light, and the reflection of light and sound. A stickhalf-immersed in water always _looks_ broken, however well we may knowthat the appearance is due to the bending of the rays of light. Similarly, an echo always sounds as though it came from some object inthe direction in which the air-waves finally travel to the ear, thoughwe are perfectly sure that these undulations have taken a circuitouscourse. It is hardly necessary to remind the reader that the deeplyorganized tendency to mistake the direction of the visible or audibleobject in these cases has from remote ages been made use of as a meansof popular delusion. Thus, we are told by Sir D. Brewster, in hisentertaining _Letters on Natural Magic_ (letter iv. ), that the concavemirror was probably used as the instrument for bringing the gods beforethe people. The throwing of the images formed by such mirrors upon smokeor against fire, so as to make them more distinct, seems to have been afavourite device in the ancient art of necromancy. Closely connected with these illusions of direction with respect toresting objects, are those into which we are apt to fall respecting themovements of objects. What looks like the movement of something acrossthe field of vision is made known to us either by the feeling of theocular muscles, if the eye follows the object, or through the sequenceof locally distinct retinal impressions, if the eye is stationary. Now, either of these effects may result, not only from the actual movement ofthe object in a particular direction, but from our own movement in anopposite direction; or, again, from our both moving in the firstdirection, the object more rapidly than ourselves; or, finally, from ourboth moving in an opposite direction to this, ourselves more rapidlythan the object. There is thus always a variety of conceivableexplanations, and the action of past experience and association showsitself very plainly in the determination of the direction ofinterpretation. Thus, it is our instinctive tendency to take apparentmovement for real movement, except when the fact of our own movement isclearly present to consciousness, as when we are walking, or when we aresitting behind a horse whose movement we see. And so when the sense ofour own movement becomes indistinct, as in a railway carriage, wenaturally drift into the illusion that objects, such as trees, telegraphposts, and so on, are moving, when they are perfectly still. Under thesame circumstances, we are apt to suppose that a train which is justshooting ahead of us is moving slowly. Similar uncertainties arise with respect to the relative movement of twoobjects, the eye being supposed to be fixed in space. When two objectsseem to pass one another, it may be that they are both moving incontrary directions, or that one only is moving, or finally, that bothare moving in the same direction, the one faster than the other. Experience and habit here again suggest the interpretation which is mosteasy, and not unfrequently produce illusion. Thus, when we watch cloudsscudding over the face of the moon, the latter seems moving rather thanthe former, and the illusion only disappears when we fix the eye on themoon and recognize that it is really stationary. The probable reason ofthis is, as Wundt suggests, that experience has made it far easier forus to think of small objects like the moon moving rapidly, than of largemasses like the clouds. [36] The perception of distance, still more than that of direction, is liableto be illusory. Indeed, the visual recognition of distance, togetherwith that of solidity, has been the great region for the study of "thedeceptions of the senses. " Without treating the subject fully here, Ishall try to describe briefly the nature and source of theseillusions. [37] Confining ourselves first of all to near objects, we know that thesmaller differences of distance in these cases are, if the eyes are atrest, perceived by means of the dissimilar pictures projected on the tworetinas; or if they move, by this means, together with the muscularfeelings that accompany different degrees of convergence of the twoeyes. This was demonstrated by the famous experiments of Wheatstone. Thus, by means of the now familiar stereoscope, he was able to produce aperfect illusion of relief. The stereoscope may be said to introduce anexceptional state of things into the spectator's environment. Itimitates, by means of two flat drawings, the dissimilar retinal picturesprojected by a single solid receding object, and the lenses throughwhich the eyes look are so constructed as to compel them to converge asthough looking on a single object. And so powerful is the tendency tointerpret this impression as one of solidity, that even though we areaware of the presence of the stereoscopic apparatus, we cannot helpseeing the two drawings as a single solid object. In the case of more remote objects, there is no dissimilarity of theretinal pictures or feelings of convergence to assist the eye indetermining distance. Here its judgment, which now becomes more of aprocess of _conscious_ inference, is determined by a number ofcircumstances which, through experience and association, have become thesigns of differences of depth in space. Among these are the degree ofindistinctness of the impression, the apparent or retinal magnitude (ifthe object is a familiar one), the relations of linear perspective, asthe interruption of the outline of far objects by that of near objects, and so on. In a process so complicated there is clearly ample room forerror, and wrong estimates of distance whenever unusual circumstancesare present are familiar to all. Thus, the inexperienced Englishtourist, when in the clear atmosphere of Switzerland, where theimpressions from distant objects are more distinct than at home, naturally falls into the illusion that the mountains are much nearerthan they are, and so fails to realize their true altitude. _Illusions of Art. _ The imitation of solidity and depth by art is a curious and interestingillustration of the mode of production of illusion. Here we are not, ofcourse, concerned with the question how far illusion is desirable inart, but only with its capabilities of illusory presentment; whichcapabilities, it may be added, have been fully illustrated in thehistory of art. The full treatment of this subject would form a chapterin itself; here I can only touch on its main features. Pictorial art working on a flat surface cannot, it is plain, imitate thestereoscope, and produce a perfect sense of solidity. Yet it manages toproduce a pretty strong illusion. It illustrates in a striking mannerthe ease with which the eye conceives relations of depth or relief andsolidity. If, for example, on a carpet, wall-paper, or dress, brightlines are laid on a dark colour as ground, we easily imagine that theyare advancing. The reason of this seems to be that in our dailyexperience advancing surfaces catch and reflect the light, whereasretiring surfaces are in shadow. [38] The same principle is illustrated in one of the means used by the artistto produce a strong sense of relief, namely, the cast shadow. A circledrawn with chalk with a powerful cast shadow on one side will, withoutany shading or modelling of the form, appear to stand out from thepaper, thus: [Illustration: FIG. 1. ] The reason is that the presence of such a shadow so forcibly suggests tothe mind that the object is a prominent one intervening between thelight and the shaded surface. [39] Even without differences of light and shade, by a mere arrangement oflines, we may produce a powerful sense of relief or solidity. A strikingexample of this is the way in which two intersecting lines sometimesappear to recede from the eye, as the lines _a a'_, _b b'_, in the nextdrawing, which seem to belong to a regular pattern on the ground, atwhich the eye is looking from above and obliquely. [Illustration: FIG. 2. ] Again, the correct delineation of the projection of a regulargeometrical figure, as a cube, suffices to give the eye a sense ofrelief. This effect is found to be the more striking in proportion tothe familiarity of the form. The following drawing of a long box-shapedsolid at once seems to stand out to the eye. [Illustration: FIG. 3. ] This habitual interpretation of the flat in art as answering to objectsin relief, or having depth, can only be understood when it is rememberedthat our daily experience gives us myriads of instances in which theeffect of such flat representations answers to solid receding forms. That is to say, in the case of all distant objects, in the perception ofwhich the dissimilarity of the retinal pictures and the feeling ofconvergence take no part, we have to interpret solidity, and relationsof nearer and further, by such signs as linear perspective and castshadow. On the other hand, it is only in the artificial life of indoors, on our picture-covered walls, that we experience such effects withoutdiscovering corresponding realities. Hence a deeply organized habit oftaking these impressions as answering to the solid and not to the flat. If our experience had been quite different; if, for example, we hadbeen brought up in an empty room, amid painted walls, and had beenexcluded from the sight of the world of receding objects outside, wemight easily have formed an exactly opposite habit of taking the actualmountains, trees, etc. , of the distant scene to be pictures laid on aflat surface. [Illustration: FIG. 4. ] It follows from this that, with respect to the distant parts of a scene, pictorial art possesses the means of perfect imitation; and here we seethat a complete illusory effect is obtainable. I need but to refer tothe well-known devices of linear and aerial perspective, by which thisresult is secured. [40] The value of these means of producing illusion atthe command of the painter, may be illustrated by the following fact, which I borrow from Helmholtz. If you place two pieces of cardboardwhich correspond to portions of one form at the sides and in front of athird piece, in the way represented above, so as just to allow the eyeto follow the contour of this last, and then look at this arrangementfrom a point at some little distance with one eye, you easily supposethat it stands in front of the side pieces. The explanation of theillusion is that this particular arrangement powerfully suggests thatthe outline of the whole figure, of which the two side pieces are parts, is broken by an intervening object. Owing to the force of these andother suggestions, it is easy for the spectator, when attending to thebackground of a landscape painting, to give himself up for a moment tothe pleasant delusion that he is looking at an actual receding scene. In connection with pictorial delusion, I may refer to the well-knownfact, that the eye in a portrait seems to follow the spectator, or thata gun, with its muzzle pointing straight outwards, appears to turn asthe spectator moves. [41] These tricks of art have puzzled many people, yet their effect is easily understood, and has been very clearlyexplained by Sir D. Brewster, in the work already referred to (letterv. ). They depend on the fact that a painting, being a flat projectiononly and not a solid, continues to present the front view of an objectwhich it represents wherever the spectator happens to stand. Were theeye in the portrait a real eye, a side movement of the spectator would, it is evident, cause him to see less of the pupil and more of the sideof the eyeball, and he would only continue to see the full pupil whenthe eye followed him. We regard the eye in the picture as a real eyehaving relief, and judge accordingly. We may fall into similar illusions respecting distance in auditoryperception. A change of wind, an unusual stillness in the air, is quitesufficient to produce the sense that sounding objects are nearer thanthey actually are. The art of the ventriloquist manifestly aims atproducing this kind of illusion. By imitating the dull effect of adistant voice, he is able to excite in the minds of his audience apowerful conviction that the sounds proceed from a distant point. Thereis little doubt that ventriloquism has played a conspicuous part in thearts of divination and magic. _Misconception of Local Arrangement. _ Let us now pass to a class of illusions closely related to those havingto do with distance, but involving some special kind of circumstancewhich powerfully suggests a particular arrangement in space. One of themost striking examples of these is the erroneous localization of aquality in space, that is to say, the reference of it to an objectnearer, or further off than the right one. Thus, when we look through apiece of yellow glass at a dull, wintry landscape, we are disposed toimagine that we are looking at a sunny scene of preternatural warmth. Amoment's reflection would tell us that the yellow tint, with which theobjects appear to be suffused, comes from the presence of the glass;yet, in spite of this, the illusion persists with a curious force. Theexplanation is, of course, that the circumstances are exceptional, thatin a vast majority of cases the impression of colour belongs to theobject and not to an intervening medium, [42] and that consequently wetend to ignore the glass, and to refer the colour to the objectsthemselves. When, however, the fact of the existence of a coloured medium isdistinctly present to the mind, we easily learn to allow for this, andto recognize one coloured surface correctly through a recognized medium. Thus, we appear to ourselves to see the reflected images of the wall, etc. , of a room, in a bright mahogany table, not suffused with a reddishyellow tint, as they actually are--and may be seen to be by the simpledevice of looking at a small bit of the image through a tube, but intheir ordinary colour. We may be said to fall into illusion here in sofar as we overlook the exact quality of the impression actually made onthe eye. This point will be touched on presently. Here I am concerned toshow that this habit of allowing for the coloured medium may, in itsturn, occasionally lead to plain and palpable illusion. The most striking example of this error is to be met with among thecurious phenomena of colour-contrast already referred to. In many ofthese cases the appearance of the contrasting colour is, as I haveobserved, due to a temporary modification of the nervous substance. Yetit is found that this organic factor does not wholly account for thephenomena. For example, Meyer made the following experiment. He covereda piece of green paper by a sheet of thin transparent white paper. Thecolour of this double surface was, of course, a pale green. He thenintroduced a scrap of grey paper between the two sheets, and found that, instead of looking whitish as it really was, it looked rose-red. Whatever the colour of the under sheet the grey scrap took thecomplementary hue. If, however, the piece of grey paper is put outsidethe thin sheet, it looks grey; and what is most remarkable is that whena second piece is put outside, the scrap inside no longer wears thecomplementary hue. There is here evidently something more than a change of organicconditions; there is an action of experience and suggestion. The reasonof our seeing the scrap rose-red in one case and neutral grey inanother, is that in the first instance we vividly represent to ourselvesthat we are looking at it through a greenish veil (which is, of course, a part of the illusion); for rose-red seen through a greenish mediumwould, as a matter of fact, be light grey, as this scrap is. Even if weallow that there always exists after an impression of colour a temporaryorganic disposition to see the complementary hue, this does not sufficeas an explanation of these cases; we have to conclude further thatimagination, led by the usual run of our experience, is here aco-operant factor, and helps to determine whether the complementary tintshall be seen or not. _Misinterpretation of Form. _ More complex and circumscribed associations take part in those errorswhich we occasionally commit respecting the particular form of objects. This has already been touched on in dealing with artistic illusion. Thedisposition of the eye to attribute solidity to a flat drawing is themore powerful in proportion to the familiarity of the form. Thus, anoutline drawing of a building is apt to stand out with special force. Another curious illustration of this is the phenomenon known as theconversion of the concave mould or matrix of a medal into thecorresponding convex relief. If, says Helmholtz, the mould of a medal beilluminated by a light falling obliquely so as to produce strongshadows, and if we regard this with one eye, we easily fall into theillusion that it is the original raised design, illuminated from _theopposite side_. As a matter of fact, the visual impression produced by aconcave form with the light falling on one side, very closely resemblesthat produced by a corresponding convex form with the light falling onthe other side. At the same time, it is found that the opposite mode ofconversion, that is to say, the transformation of the raised into thedepressed form, though occurring occasionally, is much less frequent. Now, it may be asked, why should we tend to transform the concave intothe convex, rather than the convex into the concave? The reader mayeasily anticipate the answer from what has been said about the deeplyfixed tendency of the eye to solidify a plane surface. We are renderedmuch more familiar, both by nature and by art, with raised (_cameo_)design than with depressed design (_intaglio_), and we instinctivelyinterpret the less familiar form by the more familiar. This explanationappears to be borne out by the fact emphasized by Schroeder that theillusion is much more powerful if the design is that of some well-knownobject, as the human head or figure, or an animal form, or leaves. [43] Another illustration of this kind of illusion recently occurred in myown experience. Nearly opposite to my window came a narrow space betweentwo detached houses. This was, of course, darker than the front of thehouses, and the receding parallel lines of the bricks appeared to crossthis marrow vertical shaft obliquely. I could never look at this withoutseeing it as a convex column, round which the parallel lines woundobliquely. Others saw it as I did, though not always with the sameoverpowering effect. I can only account for this illusion by help of thegeneral tendency of the eye to solidify impressions drawn from the flat, together with the effect of special types of experience, moreparticularly the perception of cylindrical forms in trees, columns, etc. It may be added that a somewhat similar illustration of the action ofspecial types of experience on the perception of individual form may befound in the region of hearing. The powerful disposition to take thefinely graduated cadences of sound produced by the wind for theutterances of a Iranian voice, is due to the fact that this particularform and arrangement of sound has deeply impressed itself on our minds, in connection with numberless utterances of human feeling. _Illusions of Recognition. _ As a last illustration of comparatively passive illusions, I may referto the errors which we occasionally commit in recognizing objects. As Ihave already observed, the process of full and clear recognition, specific and individual, involves a classing of a number of distinctaspects of the object, such as colour, form, etc. Accordingly, when in aperfectly calm state of mind we fall into illusion with respect to anyobject plainly visible, it must be through some accidental resemblancebetween the object and the other object or class of objects with whichwe identify it. In the case of individual identification such illusionsare, of course, comparatively rare, since here there are involved somany characteristic differences. On the other hand, in the case ofspecific recognition there is ample room for error, especially in thosekinds of more subtle recognition to which I have already referred. To"recognize" a person as a Frenchman or a military man, for example, isoften an erroneous process. Logicians have included this kind of errorunder what they call "fallacies of observation. " Errors of recognition, both specific and individual, are, of course, more easy in the case of distant objects or objects otherwiseindistinctly seen. It is noticeable in these cases that, even whenperfectly cool and free from emotional excitement, we tend to interpretsuch indistinct impressions according to certain favourite types ofexperience, as the human face and figure. Our interpretative imaginationeasily sees traces of the human form in cloud, rock, or tree-stump. Again, even when there is no error of recognition, in the sense ofconfusing one object with other objects, there may be partial illusion. I have remarked that the process of recognizing an object commonlyinvolves an overlooking of points of diversity in the object, or aspectof the object, now present. And sometimes this inattention to what isactually present includes an error as to the actual visual sensation ofthe moment. Thus, for example, when I look at a sheet of white paper ina feebly lit room, I seem to see its whiteness. If, however, I bring itnear the window, and let the sun fall on a part of it, I at oncerecognize that what I have been seeing is not white, but a decided grey. Similarly, when I look at a brick viaduct a mile or two off, I appear tomyself to recognize its redness. In fact, however, the impression ofcolour which I receive from the object is not that of brick-red at all, but a much less decided tint; which I may easily prove by bending myhead downwards and letting the scene image itself on the retina in anunusual way, in which case the recognition of the object as a viaductbeing less distinct, I am better able to attend to the exact shade ofthe colour. Nowhere is this inattention to the sensation of the moment exhibited inso striking a manner as in pictorial art. A picture of Meissonier maygive the eye a representation of a scene in which the objects, as thehuman figures and horses, have a distinctness that belongs to nearobjects, but an apparent magnitude that belongs to distant objects. Soagain, it is found that the degree of luminosity or brightness of apictorial representation differs in general enormously from that of theactual objects. Thus, according to the calculations of Helmholtz, [44] apicture representing a Bedouin's white raiment in blinding sunshine, will, when seen in a fairly lit gallery, have a degree of luminosityreaching only to about one-thirtieth of that of the actual object. Onthe other hand, a painting representing marble ruins illuminated bymoonlight, will, under the same conditions of illumination, have aluminosity amounting to as much as from ten to twenty thousand timesthat of the object. Yet the spectator does not notice these stupendousdiscrepancies. The representation, in spite of its vast difference, atonce carries the mind on to the actuality, and the spectator may evenappear to himself, in moments of complete absorption, to be looking atthe actual scene. The truly startling part of these illusions is, that the direct resultof sensory stimulation appears to be actually displaced by a mentalimage. Thus, in the case of Meyer's experiment, of looking at thedistant viaduct, and of recognizing an artistic representation, imagination seems in a measure to take the place of sensation, or toblind the mind to what is actually before it. The mystery of the process, however, greatly disappears when it isremembered that what we call a conscious "sensation" is reallycompounded of a result of sensory stimulation and a result of centralreaction, of a purely passive impression and the mental activityinvolved in attending to this and classing it. [45] This being so, asensation may be modified by anything exceptional in the mode of centralreaction of the moment. Now, in all the cases just considered, we haveone common feature, a powerful suggestion of the presence of aparticular object or local arrangement. This suggestion, taking the formof a vivid mental image, dominates and overpowers the passiveimpression. Thus, in Meyer's experiment, the mind is possessed by thesupposition that we are looking at the grey spot through a greenishmedium. So in the case of the distant viaduct, we are under the masteryof the idea that what we see in the distance is a red brick structure. Once more, in the instance of looking at the picture, the spectator'simagination is enchained by the vivid representation of the object forwhich the picture stands, as the marble ruins in the moonlight or theBedouin in the desert. It may be well to add that this mental uncertainty as to the exactnature of a present impression is necessitated by the very conditions ofaccurate perception. If, as I have said, all recognition takes place byoverlooking points of diversity, the mind must, in course of time, acquire a habit of not attending to the exact quality ofsense-impressions in all cases where the interpretation seems plain andobvious. Or, to use Helmholtz's words, our sensations are, in a generalway, of interest to us only as signs of things, and if we are sure ofthe thing, we readily overlook the precise nature of the impression. Inshort, we get into the way of attending only to what is essential, constant, and characteristic in objects, and disregarding what isvariable and accidental. [46] Thus, we attend, in the first place, to theform of objects, the most constant and characteristic element of all, being comparatively inattentive to colour, which varies with distance, atmospheric changes, and mode of illumination. So we attend to therelative magnitude of objects rather than to the absolute, and to therelative intensities of light and shade rather than to the absolute; forin so doing we are noting what is constant for all distances and modesof illumination, and overlooking what is variable. And the success ofpictorial art depends on the observance of this law of perception. These remarks at once point out the limits of these illusions. In normalcircumstances, an act of imagination, however vivid, cannot create thesemblance of a sensation which is altogether absent; it can onlyslightly modify the actual impression by interfering with that processof comparison and classification which enters into all definitedetermination of sensational quality. Another great fact that has come to light in the investigation of theseillusions is that oft-recurring and familiar types of experience leavepermanent dispositions in the mind. As I said when describing theprocess of perception, what has been frequently perceived is perceivedmore and more readily. It follows from this that the mind will behabitually disposed to form the corresponding mental images, and tointerpret impressions by help of these. The range of artistic suggestiondepends on this. A clever draughtsman can indicate a face by a few roughtouches, and this is due to the fact that the spectator's mind is sofamiliarized, through recurring experience and special interest, withthe object, that it is ready to construct the requisite mental image atthe slightest external suggestion. And hence the risk of hasty andillusory interpretation. These observations naturally conduct us to the consideration of thesecond great group of sense-illusions, which I have marked off as activeillusions, where the action of a pre-existing intellectual dispositionbecomes much more clearly marked, and assumes the form of a freeimaginative transformation of reality. CHAPTER VI. ILLUSIONS OF PERCEPTION--_continued_. B. _Active Illusions. _ When giving an account of the mechanism of perception, I spoke of anindependent action of the imagination which tends to anticipate theprocess of suggestion from without. Thus, when expecting a particularfriend, I recognize his form much more readily than when my mind has notbeen preoccupied with his image. A little consideration will show that this process must be highlyfavourable to illusion. To begin with, even if the preperception becorrect, that is to say, if it answer to the perception, the mere factof vivid expectation will affect the exact moment of the completed actof perception. And recent experiment shows that in certain cases such aprevious activity of expectant attention may even lead to the illusorybelief that the perception takes place before it actually does. [47] A more palpable source of error resides in the risk of the formation ofan inappropriate preperception. If a wrong mental image happens to havebeen formed and vividly entertained, and if the actual impression fitsin to a certain extent with this independently formed preperception, wemay have a fusion of the two which exactly simulates the form of acomplete percept. Thus, for example, in the case just supposed, ifanother person, bearing some resemblance to our expected friend, chancesto come into view, we may probably stumble into the error of taking oneperson for another. On the physical side, we may, agreeably to the hypothesis mentionedabove, express this result by saying that, owing to a partial identityin the nervous processes involved in the anticipatory image and theimpression, the two tend to run one into the other, constituting onecontinuous process. There are different ways in which this independent activity of theimagination may falsify our perceptions. Thus, we may voluntarily chooseto entertain a certain image for the moment, and to look at theimpression in a particular way, and within certain limits suchcapricious selection of an interpretation is effectual in giving aspecial significance to an impression. Or the process of independentpreperception may go on apart from our volitions, and perhaps in spiteof these, in which case the illusion has something of the irresistiblenecessity of a passive illusion. Let us consider separately each modeof production. _Voluntary Selection of Interpretation. _ The action of a capricious exercise of the imagination in relation to animpression is illustrated in those cases where experience and suggestionoffer to the interpreting mind an uncertain sound, that is to say, wherethe present sense-signs are ambiguous. Here we obviously have a choiceof interpretation. And it is found that, in these cases, what we seedepends very much on what we wish to see. The interpretation adopted isstill, in a sense, the result of suggestion, but of one particularsuggestion which the fancy of the moment determines. Or, to put itanother way, the caprice of the moment causes the attention to focusitself in a particular manner, to direct itself specially to certainaspects and relations of objects. The eye's interpretation of movement, already referred to, obviouslyoffers a wide field for this play of selective imagination. When lookingout of the window of a railway carriage, I can at will picture to mymind the trees and telegraph posts as moving objects. Sometimes the trueinterpretation is so uncertain that the least inclination to view thephenomenon in one way determines the result. This is illustrated in acurious observation of Sinsteden. One evening, on approaching a windmillobliquely from one side, which under these circumstances he saw only asa dark silhouette against a bright sky, he noticed that the sailsappeared to go, now in one direction, now in another, according as heimagined himself looking at the front or at the back of thewindmill. [48] In the interpretation of geometrical drawings, as those of crystals, there is, as I have observed, a general tendency to view the flatdelineation as answering to a raised object, or a body in relief, according to the common run of our experience. Yet there are cases whereexperience is less decided, and where, consequently, we may regard anyparticular line as advancing or receding. And it is found that when wevividly imagine that the drawing is that of a convex or concave surface, we see it to be so, with all the force of a complete perception. Theleast disposition to see it in the other way will suffice to reverse theinterpretation. Thus, in the following drawing, the reader can easilysee at will something answering to a truncated pyramid, or to theinterior of a cooking vessel. [Illustration: FIG. 5. ] Similarly, in the accompanying figure of a transparent solid, I can atwill select either of the two surfaces which approximately face the eyeand regard it as the nearer, the other appearing as the hinder surfacelooked at through the body. [Illustration: FIG. 6. ] Again, in the next drawing, taken from Schroeder, one may, by an effortof will, see the diagonal step-like pattern, either as the view fromabove of the edge of an advancing piece of wall at _a_, or as the viewfrom below of the edge of an advancing (overhanging) piece of wall at_b_. [Illustration: FIG. 7. ] These last drawings are not in true perspective on either of thesuppositions adopted, wherefore the choice is easier. But even when anoutline form is in perspective, a strenuous effort of imagination maysuffice to bring about a conversion of the appearance. Thus, if thereader will look at the drawing of the box-like solid (Fig. 3, p. 79), he will find that, after a trial or two, he succeeds in seeing it as a_concave_ figure representing the coyer and two sides of a box as lookedat from within. [49] Many of my readers, probably, share in my power of variouslyinterpreting the relative position of bands or stripes on fabrics suchas wall-papers, according to wish. I find that it is possible to viewnow this stripe or set of stripes as standing out in relief upon theothers as a ground, now these others as advancing out of the first as abackground. The difficulty of selecting either interpretation at willbecomes greater, of course, in those cases where there is a powerfulsuggestion of some particular local arrangement, as, for example, thecase of patterns much brighter than the ground, and especially of suchas represent known objects, as flowers. Yet even here a strong effort ofimagination will often suffice to bring about a conversion of the firstappearance. A somewhat similar choice of interpretation offers itself in looking atelaborate decorative patterns. When we strongly imagine any number ofdetails to be elements of one figure, they seem to become so; and agiven detail positively appears to alter in character according as it isviewed as an element of a more or less complex figure. These examples show what force belongs to a vivid preconception, if thishappens to fit only very roughly the impression of the moment, that isto say, if the interpretative image is one of the possible suggestionsof the impression. The play of imagination takes a wider range in thosecases where the impression is very indefinite in character, easilyallowing of a considerable variety of imaginative interpretation. I referred at the beginning of this account of sense-illusions to thereadiness with which the mind deceives itself with respect to the natureand causes of the vague sensations which usually form the dim backgroundof our mental life. A person of lively imagination, by trying to viewthese in a particular way, and by selectively attending to those aspectsof the sensation which answer to the caprice of the moment, may give avariety of interpretations to one and the same set of sensations. Forexample, it is very easy to get confused with respect to those tactualand motor feelings which inform us of the position of our bodilymembers. And so, when lying in bed, and attending to the sensationsconnected with the legs, we may easily delude ourselves into supposingthat these members are arranged in a most eccentric fashion. Similarly, by giving special heed to the sensations arising in connection with thecondition of the skin at any part, we may amuse ourselves with thestrangest fancies as to what is going on in these regions. Again, when any object of visual perception is indistinct or indefinitein form, there is plainly an opening for this capricious play of fancyin transforming the actual. This is illustrated in the well-knownpastime of discovering familiar forms, such as those of the human headand animals, in distant rocks and clouds, and of seeing pictures in thefire, and so on. The indistinct and indefinite shapes of the masses ofrock, cloud, or glowing coal, offer an excellent field for creativefancy, and a person of lively imagination will discover endless forms inwhat, to an unimaginative eye, is a formless waste. Johannes Müllerrelates that, when a child, he used to spend hours in discovering theoutlines of forms in the partly blackened and cracked stucco of thehouse that stood opposite to his own. [50] Here it is plain that, whileexperience and association are not wholly absent, but place certain widelimits on this process of castle-building, the spontaneous activity ofthe percipient mind is the great determining force. So much as to the influence of a perfectly unfettered voluntaryattention on the determination of the stage of preperception, and, through this, of the resulting interpretation. Let us now pass to casesin which this direction of preperception follows not the caprice of themoment, but the leading of some fixed predisposition in theinterpreter's mind. In these cases attention is no longer free, butfettered, only it is now fettered rather from within than from without;that is to say, the dominating preperception is much more the result ofan independent bent of the imagination than of some suggestion forced onthe mind by the actual impression of the moment. _Involuntary Mental Preadjustment. _ If we glance back at the examples of capricious selection just noticed, we shall see that they are really limited not only by the character ofthe impression of the time, but also by the mental habits of thespectator. That is to say, we find that his fancy runs in certaindefinite directions, and takes certain habitual forms. It has alreadybeen observed that the percipient mind has very different attitudes withrespect to various kinds of impression. Towards some it holds itself ata distance, while towards others it at once bears itself familiarly; theformer are such as answer to its previous habit and bent of imagination, the latter such as do not so answer. This bent of the interpretative imagination assumes, as we have alreadyseen, two forms, that of a comparatively permanent disposition, and thatof a temporary state of expectation or mental preparedness. Illusion mayarise in connection with either of these forms. Let us illustrate bothvarieties, beginning with those which are due to a lasting mentaldisposition. It is impossible here to specify all the causes of illusion residing inorganized tendencies of the mind. The whole past mental life, with itsparticular shade of experience, its ruling emotions, and its habitualdirection of fancy, serves to give a particular colour to newimpressions, and so to favour illusion. There is a "personal equation"in perception as in belief--an amount of erroneous deviation from thecommon average view of external things, which is the outcome ofindividual temperament and habits of mind. Thus, a naturally timid manwill be in general disposed to see ugly and fearful objects where aperfectly unbiased mind perceives nothing of the kind; and the formswhich these objects of dread will assume are determined by the characterof his past experience, and by the customary direction of hisimagination. In perfectly healthy states of mind this influence of temperament andmental habit on the perception of external objects is, of course, verylimited; it shows itself more distinctly, as we shall see, in modifyingthe estimate of things in relation to the æsthetic and other feelings. This applies to the mythical poetical way of looking at nature--a partof our subject to which we shall have to return later on. Passing now from the effect of such permanent dispositions, let us lookat the more striking results of temporary expectancy of mind. When touching on the influence of such a temporary mental attitude inthe process of correct perception, I remarked that this readiness ofmind might assume an indefinite or a definite form. We will examine theeffect of each kind in the production of illusion. _Action of Sub-Expectation. _ First of all, then, our minds may at the particular moment be disposedto entertain any one of a vaguely circumscribed group of images. Thus, to return to the example already referred to, when in Italy, we are in astate of readiness to frame any of the images that we have learnt toassociate with this country. We may not be distinctly anticipating anyone kind of object, but are nevertheless in a condition of_sub-expectation_ with reference to a large number of objects. Accordingly, when an impression occurs which answers only very roughlyto one of the associated images, there is a tendency to superimpose theimage on the impression. In this way illusion arises. Thus, a man, whenstrolling in a cathedral, will be apt to take any kind of faint hollowsound for the soft tones of an organ. The disposition to anticipate fact and reality in this way will be allthe stronger if, as usually happens, the mental images thus lying readyfor use have an emotional colouring. Emotion is the great disturber ofall intellectual operations. It effects marvellous things, as we shallpresently see, in the region of illusory belief, and its influence isvery marked in the seemingly cooler region of external perception. Theeffect of any emotional excitement appears to be to give a preternaturalvividness and persistence to the ideas answering to it, that is to say, the ideas which are its excitants, or which are otherwise associatedwith it. Owing to this circumstance, when the mind is under thetemporary sway of any feeling, as, for example, fear, there will be aspecial readiness to interpret objects by help of images congruent withthe emotion. Thus, a man under the control of fear will be ready to seeany kind of fear-inspiring object whenever there is any resemblance tosuch in the things actually present to his vision. The state of awewhich the surrounding circumstances of a spiritualist _séance_ inspiresproduces a general readiness of mind to perceive what is strange, mysterious, and apparently miraculous. It is worth noting, perhaps, that those delightful half-illusions whichimitative art seeks to produce are greatly favoured by such a temporaryattitude of the interpreting imagination. In the theatre, for example, we are prepared for realizing the semblance of life that is to beunfolded before us. We come knowing that what is to be performed aims atrepresenting a real action or actual series of events. We not improbablywork ourselves into a slightly excited state in anticipation of such arepresentation. More than this, as the play progresses, the realizationof what has gone before produces a strong disposition to believe in thereality of what is to follow. And this effect is proportionate to thedegree of coherence and continuity in the action. In this way, there isa cumulative effect on the mind. If the action is good, the illusion, asevery play-goer knows, is most complete towards the end. Were it not for all this mental preparation, the illusory character ofthe performance would be too patent to view, and our enjoyment wouldsuffer. A man is often aware of this when coming into a theatre duringthe progress of a piece before his mind accommodates itself to themeaning of the play. And the same thing is recognizable in the fact thatthe frequenter of the theatre has his susceptibility to histrionicdelusion increased by acquiring a habit of looking out for the meaningof the performance. Persons who first see a play, unless they be ofexceptional imagination and have thought much about the theatre--asCharlotte Brontë, for instance--hardly feel the illusion at all. Atleast, this is true of the opera, where the departure from reality isso striking that the impression can hardly fail to be a ludicrous one, till the habit of taking the performance for what it is intended to beis fully formed. [51] A similar effect of intellectual preadjustment is observable in thefainter degrees of illusion produced by pictorial art. Here theundeceiving circumstances, the flat surface, the surroundings, and soon, would sometimes be quite sufficient to prevent the least degree ofillusion, were it not that the spectator comes prepared to see arepresentation of some real object. This is our state of mind when weenter a picture gallery or approach what we recognize as a picture onthe wall of a room. A savage would not "realize" a slight sketch as soonas one accustomed to pictorial representation, and ready to perform therequired interpretative act. [52] So much as to the effect of an indefinite state of sub-expectation inmisleading our perceptions. Let us now glance at the results of definitepreimagination, including what are generally known as expectations. _Effects of Vivid Expectation. _ Such expectations may grow out of some present objective facts, whichserve as signs of the expected event; or they may arise by way of verbalsuggestion; or, finally, they may be due to internal spontaneousimagination. In the first place, then, the expectations may grow out of previousperceptions, while, nevertheless, the direction of the expectation maybe a wrong one. Here the interpreting imagination is, in a large sense, under the control of external suggestion, though, with respect to theparticular impression that is misconstrued, it may be regarded as actingindependently and spontaneously. Illustrations of this effect in producing illusion will easily occur tothe reader. If I happen to have heard that a particular person has beena soldier or clergyman, I tend to see the marks of the class in thisperson, and sometimes find that this process of recognition isaltogether illusory. Again, let us suppose that a person is expecting afriend by a particular train. A passenger steps out of the train bearinga superficial resemblance to his friend; in consequence of which hefalls into the error of false identification. The delusions of the conjuror depend on a similar principle. Theperformer tells his audience that he is about to do a certain thing, forexample, take a number of animals out of a small box which is incapableof holding them. The hearers, intent on what has been said, vividlyrepresent to themselves the action described. And in this way theirattention becomes bribed, so to speak, beforehand, and fails to noticethe inconspicuous movements which would at once clear up the mystery. Similarly with respect to the illusions which overtake people atspiritualist _séances_. The intensity of the expectation of a particularkind of object excludes calm attention to what really happens, and theslightest impressions which answer to signs of the object anticipatedare instantly seized by the mind and worked up into illusoryperceptions. It is to be noted that even when the impression cannot be made to tallyexactly with the expectation, the force of the latter often effects agrotesque confusion of the perception. If, for example, a man goes intoa familiar room in the dark in order to fetch something, and for amoment forgets the particular door by which he has entered, his definiteexpectation of finding things in a certain order may blend with theorder of impressions experienced, producing for the moment a mostcomical illusion as to the actual state of things. When the degree of expectation is unusually great, it may suffice toproduce something like the counterfeit of a real sensation. This happenswhen the present circumstances are powerfully suggestive of an immediateevent. The effect is all the more powerful, moreover, in those caseswhere the object or event expected is interesting or exciting, sincehere the mental image gains in vividness through the emotionalexcitement attending it. Thus, if I am watching a train off and knowfrom all the signs that it is just about to start, I easily deludemyself into the conviction that it has begun to start, when it isreally still. [53] An intense degree of expectation may, in such cases, produce something indistinguishable from an actual sensation. Thiseffect is seen in such common experiences as that the sight of foodmakes the mouth of a hungry man water; that the appearance of a surgicalinstrument produces a nascent sensation of pain; and that a threateningmovement, giving a vivid anticipation of tickling, begets a feelingwhich closely approximates to the result of actual tickling. One or two very striking instances of such imagined sensations are givenby Dr. Carpenter. [54] Here is one. An officer who superintended theexhuming of a coffin rendered necessary through a suspicion of crime, declared that he already experienced the odour of decomposition, thoughit was afterwards found that the coffin was empty. [55] It is, of course, often difficult to say, in such cases as these, howfar elements of actual sensation co-operate in the production of theillusions. Thus, in the case just mentioned, the odour of the earth mayhave been the starting-point in the illusion. In many cases, however, animaginative mind appears to be capable of transforming a vividexpectation into a nascent stage of sensation. Thus, a mother thinkingof her sick child in an adjoining room, and keenly on the alert for itsvoice, will now and again fancy she really hears it when others hearnothing at all. _Transition to Hallucination. _ It is plain that in these cases illusion approaches to hallucination. Imagination, instead of waiting on sensation, usurps its place andimitates its appearance. Such a "subjective" sensation produced by apowerful expectation might, perhaps, by a stretch of language, beregarded as an illusion, in the narrow sense, in so far as it depends onthe suggestive force of a complete set of external circumstances; on theother hand, it is clearly an hallucination in so far as it is theproduction of the semblance of an external impression without anyexternal agency corresponding to this. In the class of illusory expectations just considered the immediatelypresent environment still plays a part, though a much less direct partthan that observable in the first large group of illusions. We will nowpass to a second mode of illusory expectation, where imagination isstill more detached from the present surroundings. A common instance of this kind of expectation is the so-called"intuition, " or presentiment; that something is going to happen, whichexpectation has no basis in fact. It does not matter whether theexpectation has arisen by way of another's words or by way of personalinclinations. A strong wish for a thing will, in an exalted state ofmind, beget a vivid anticipation of it. This subject will be touched onagain under the Illusions of Belief. Here I am concerned to point outthat such presentiments are fertile sources of sense-illusion. Thehistory of Church miracles, visions, and the like amply illustrates theeffect of a vivid anticipation in falsifying the perceptions of externalthings. In persons of a lively imagination any recent occupation of the mindwith a certain kind of mental image may suffice to beget somethingequivalent to a powerful mode of expectation. For example, we are toldby Dr. Tuke that on one occasion a lady, whose imagination had beendwelling on the subject of drinking fountains, "thought she saw in aroad a newly erected fountain, and even distinguished an inscriptionupon it, namely, 'If any man thirst, let him come unto Me, and drink. 'She afterwards found that what she had actually seen was only a fewscattered stones. "[56] In many cases there seems to be a temporarypreternatural activity of the imagination in certain directions, ofwhich no very obvious explanation is discoverable. Thus, we sometimesfind our minds dwelling on some absent friend, without being able togive any reason for this mental preoccupation. And in this way arisestrong temporary leanings to illusory perception. It may be said, indeed, that all unwonted activity of the imagination, however itarises, has as its immediate result a temporary mode of expectation, definite or indefinite, which easily confuses our perceptions ofexternal things. In proportion as this pre-existing imaginative impulse becomes morepowerful, the amount of actual impression necessary to transform themental image into an illusory perception becomes less; and, what is moreimportant, this transformation of the internal image involves a largerand larger displacement of the actual impression of the moment. A manwhose mind is at the time strongly possessed by one kind of image, willtend to project this outwards with hardly any regard to the actualexternal circumstances. This state of things is most completely illustrated in many of thegrosser illusions of the insane. Thus, when a patient takes any smallobjects, as pebbles, for gold and silver, under the influence of thedominant idea of being a millionaire, it is obvious that externalsuggestion has very little to do with the self-deception. The confusionsinto which the patient often falls with respect to the persons beforehim show the same state of mind; for in many cases there is nodiscoverable individual resemblance between the person actually presentand the person for whom he is taken. It is evident that when illusion reaches this stage, it is scarcelydistinguishable from what is specially known as hallucination. As I haveremarked in setting out, illusion and hallucination shade one into theother much too gradually for us to draw any sharp line of demarcationbetween them. And here we see that hallucination differs from illusiononly in the proportion in which the causes are present. When theinternal imaginative impulse reaches a certain strength, it becomesself-sufficient, or independent of any external impression. This intimate relation between the extreme form of active illusion andhallucination may be seen, too, by examining the physical conditions ofeach. As I have already remarked, active illusion has for itsphysiological basis a state of sub-excitation, or an exceptionalcondition of irritability in the structures engaged in the act ofinterpretative imagination. The greater the degree of this irritability, the less will be the force of external stimulation needed to produce theeffect of excitation, and the more energetic will be the degree of thisexcitation. Moreover, it is plain that this increase in the strength ofthe excitation will involve an extension of the area of excitation till, by-and-by, the peripheral regions of the nervous system may be involvedjust as in the case of external stimulation. This accounts for thegradual displacement of the impression of the moment by the mentalimage. It follows that when the irritability reaches a certain degree, the amount of external stimulus needed may become a vanishing quantity, or the state of sub-excitation may of itself develop into one of fullactivity. _Hallucinations. _ I do not propose to go very fully into the description and explanationof hallucinations here, since they fall to a large extent under thecategory of distinctly pathological phenomena. Yet our study ofillusions would not be complete without a glance at this part of thesubject. Hallucination, by which I mean the projection of a mental image outwardswhen there is no external agency answering to it, assumes one of twofairly distinct forms: it may present itself either as a semblance of anexternal impression with the minimum amount of interpretation, or as acounterfeit of a completely developed percept. Thus, a visualhallucination may assume the aspect of a sensation of light or colourwhich we vaguely refer to a certain region of the external world, or ofa vision of some recognizable object. All of us frequently haveincomplete visual and auditory hallucinations of the first order, whereas the complete hallucinations of the second order arecomparatively rare. The first I shall call rudimentary, the seconddeveloped, hallucinations. Rudimentary hallucinations may have either a peripheral or a centralorigin. They may first of all have their starting-point in thosesubjective sensations which, as we have seen, are connected with certainprocesses set up in the peripheral regions of the nervous system. Or, secondly, they may originate in a certain preternatural activity of thesensory centres, or "sensorium, " in what has been called by Germanphysiologists an automatic excitation of the central structures, whichactivity may probably diffuse itself downwards to the peripheral regionsof the nerves. Baillarger would call hallucinations of the former class"psycho-sensorial, " those of the latter class purely "psychical, "hallucinations. [57] It is often a matter of great difficulty to determine which part of thenervous system is originally concerned in these rudimentaryhallucinations. It is probable that in normal life they are mostfrequently due to peripheral disturbance. And it seems reasonable tosuppose that where the hallucination remains in this initial stage of avery incompletely interpreted visual or auditory impression, whether innormal or abnormal life, its real physiological source is the periphery. For the automatic excitation of the centres would pretty certainly issuein the semblance of some definite, familiar variety of sense-impressionwhich, moreover, as a part of a complex state known as a percept, wouldinstantly present itself as a completely formed quasi-percept. In truth, we may pretty safely argue that if it is the centre which is directlythrown into a state of activity, it will be thrown into the usualcomplex, that is to say, _perceptional_, mode of activity. Let us now turn to hallucinations properly so called, that is to say, completely developed quasi-percepts. These commonly assume the form ofvisual or auditory hallucinations. Like the incomplete hallucinations, they may have their starting-point either in some disturbance in theperipheral regions of the nervous system or in the automatic activity ofthe central structures: or, to use the language of Baillarger, we maysay that they are either "psycho-sensorial" or purely "psychical. " Asubjective visual sensation, arising from certain conditions in theretina and connected portions of the optic nerve, may by chance resemblea familiar impression, and so be at once interpreted as an effect of aparticular external object. More frequently, however, the automaticactivity of the centres must be regarded, either in part or altogether, as the physiological cause of the phenomenon. This is clearly the casewhen, on the subjective side, the hallucination answers to a precedingenergetic activity of the imagination, as in the case of the visionaryand the monomaniac. Sometimes, however, as we have seen, thehallucinatory percept answers to previous prolonged acts of perception, leaving a kind of reverberation in the structures concerned; and in thiscase it is obviously impossible to say whether the peripheral or centralregions (if either) have most to do with the hallucination. [58] The classifications of the causes of hallucination to be met with in theworks of pathologists, bear out the distinction just drawn. Griesingertells us (_op. Cit. _, pp. 94, 95) that the general causes ofhallucination are: (1) Local disease of the organ of sense; (2) a stateof deep exhaustion either of mind or of body; (3) morbid emotionalstates, such as fear; (4) outward calm and stillness between sleepingand waking; and (5) the action of certain poisons, as haschisch, opium, belladonna. The first cause points pretty distinctly to a peripheralorigin, whereas the others appear to refer mainly, if not exclusively, to central derangements. Excessive fatigue appears to predispose thecentral structures to an abnormal kind of activity, and the same effectmay be brought about by emotional agitation and by the action ofpoisons. The fourth case mentioned here, absence of externalstimulation, would naturally raise the nervous structures to anexceptional pitch of excitability. Such a condition would, moreover, prove favourable to hallucination by blurring the distinction betweenmental image and actual impression. _Hallucinations of Normal Life. _ In normal life, perfect hallucinations, in the strict sense as distinctfrom illusions, are comparatively rare. Fully developed persistenthallucinations, as those of Nicolai, the Berlin bookseller, and of Mrs. A----, the lady cited by Sir D. Brewster, in his _Letters on NaturalMagic_, point to the presence of incipient nervous disorder. In healthylife, on the other hand, while everybody is familiar with subjectivesensations such as flying spots, phosphenes, ringing in the ears, fewfall into the error of seeing or hearing distinct recognizable objectsin the absence of all external impressions. In the lives of eminent menwe read of such phenomena as very occasional events. Malebranche, forexample, is said to have heard the voice of God calling him. Descartessays that, after a long confinement, he was followed by an invisibleperson, calling him to pursue his search for truth. Dr. Johnson narratesthat he once heard his absent mother calling him. Byron tells us that hewas sometimes visited by spectres. Goethe records that he once saw anexact counterpart of himself coming towards him. Sir Walter Scott issaid to have seen a phantom of the dead Byron. It is possible that allof us are liable to momentary hallucinations at times of exceptionalnervous exhaustion, though they are too fugitive to excite ourattention. When not brought on by exhaustion or artificial means, thehallucinations of the sane have their origin in a preternatural power ofimagination. It is well known that this power can be greatly improved byattention and cultivation. Goethe used to exercise himself in watchingfor ocular spectra, and could at will transform these subjectivesensations into definite forms, such as flowers; and Johannes Müllerfound he had the same power. [59] Stories are told of portrait painterswho could summon visual images of their sitters with a vividness equalto that of reality, and serving all the purposes of their art. Mr. Galton's interesting inquiries into the power of "visualizing" wouldappear to prove that many people can at will sport on the confines ofthe phantom world of hallucination. There is good reason to think thatimaginative children tend to confuse mental images and percepts. [60] _The Hallucinations of Insanity. _ The hallucinations of the insane are but a fuller manifestation offorces that we see at work in normal life. Their characteristic is thatthey simulate the form of distinctly present objects, the existence ofwhich is not instantly contradicted by the actual surroundings of themoment. [61] The hallucinations have their origin partly in subjectivesensations, which are probably connected with peripheral disturbances, partly and principally in central derangements. [62] These includeprofound emotional changes, which affect the ruling mental tone, andexert a powerful influence on the course of the mental images. Thehallucinations of insanity are due to a projection of mental imageswhich have, owing to certain circumstances, gained a preternaturalpersistence and vividness. Sometimes it is the images that have beendwelt on with passionate longing before the disease, sometimes thosewhich have grown most habitual through the mode of dailyoccupation, [63] and sometimes those connected with some incident at ornear the time of the commencement of the disease. In mental disease, auditory hallucinations play a part no lessconspicuous than visual. [64] Patients frequently complain of havingtheir thoughts spoken to them, and it is not uncommon for them toimagine that they are addressed by a number of voices at the sametime. [65] These auditory hallucinations offer a good opportunity for studying thegradual growth of centrally originating hallucinations. In the earlystages of the disease, the patient partly distinguishes hisrepresentative from his preservative sounds. Thus, he talks of sermonsbeing composed to him _in his head_. He calls these "internal voices, "or "voices of the soul. " It is only when the disease gains ground andthe central irritability increases that these audible thoughts becomedistinctly projected as external sounds into more or less definiteregions of the environment. And it is exceedingly curious to notice thedifferent directions which patients give to these sounds, referring themnow to a quarter above the head, now to a region below the floor, and soon. [66] _Range of Sense-Illusions. _ And now let us glance back to see the path we have traversed. We set outwith an account of perfectly normal perception, and found, even here, inthe projection of our sensations of colour, sound, etc. , into theenvironment or to the extremities of the organism, something which, fromthe point of view of physical science, easily wears the appearance of aningredient of illusion. Waiving this, however, and taking the word illusion as commonlyunderstood, we find that it begins when the element of imagination nolonger answers to a present reality or external fact in any sense ofthis expression. In its lowest stages illusion closely counterfeitscorrect perception in the balance of the direct factor, sensation, andthe indirect factor, mental reproduction or imagination. The degree ofillusion increases in proportion as the imaginative element gains inforce relatively to the present impression; till, in the wild illusionsof the insane, the amount of actual impression becomes evanescent. Whenthis point is reached, the act of imagination shows itself as a purelycreative process, or an hallucination. While we may thus trace the progress of illusion towards hallucinationby means of the gradual increase in force and extent of the imaginative, or indirect, as opposed to the sensuous, or direct, element inperception, we have found a second starting-point for this movement inthe mechanism of sensation, involving, as it does, the occasionalproduction of "subjective sensations. " Such sensations constitute aborder-land between the regions of illusion in the narrow sense, andhallucination. In their simplest and least developed form they may beregarded, at least in the case of hearing and sight, as partlyhallucinatory; and they serve as a natural basis for the construction ofcomplete hallucinations, or hallucinatory percepts. In these different ways, then, the slight, scarcely noticeable illusionsof normal life lead up to the most startling hallucinations of abnormallife. From the two poles of the higher centres of attention andimagination on the one side, and the lower regions of nervous actioninvolved in sensation on the other side, issue forces which may, undercertain circumstances, develop into full hallucinatory percepts. Thusclosely is healthy attached to morbid mental life. There seems to be nosudden break between our most sober every-day recognitions of familiarobjects and the wildest hallucinations of the demented. As we pass fromthe former to the latter, we find that there is never any abrupttransition, never any addition of perfectly new elements, but only thatthe old elements go on combining in ever new proportions. The connection between the illusory side of our life and insanity may beseen in another way. All illusion has as its negative condition aninterruption of the higher intellectual processes, the due control ofour mental representations by reflection and reason. In the case ofpassive illusions, the error arises from our inability to subordinatethe suggestion made by some feature of the present impression to theresult of a fuller inspection of the object before us, or of a widerreflection on the past. In other words, our minds are dominated by thepartial and the particular, to the exclusion of the total or thegeneral. In active illusions, again, the powers of judgment andreflection, including those of calm perception itself, temporarilyvacate their throne in favour of imagination. And this same suspensionof the higher intellectual functions, the stupefaction of judgment andreflection made more complete and permanent, is just what characterizesinsanity. We may, perhaps, express this point of connection between the illusionsof normal life and insanity by help of a physiological hypothesis. Ifthe nervous system has been slowly built up, during the course of humanhistory, into its present complex form, it follows that those nervousstructures and connections which have to do with the higher intellectualprocesses, or which represent the larger and more general relations ofour experience, have been most recently evolved. Consequently, theywould be the least deeply organized, and so the least stable; that isto say, the most liable to be thrown _hors de combat_. This is whathappens temporarily in the case of the sane, when the mind is held fastby an illusion. And, in states of insanity, we see the process ofnervous dissolution beginning with these same nervous structures, and sotaking the reverse order of the process of evolution. [67] And thus, wemay say that throughout the mental life of the most sane of us, thesehigher and more delicately balanced structures are constantly in dangerof being reduced to that state of inefficiency, which in its fullmanifestation is mental disease. Does this way of putting the subject seem alarming? Is it an appallingthought that our normal mental life is thus intimately related toinsanity, and graduates away into it by such fine transitions? Amoment's reflection will show that the case is not so bad as it seems. It is well to remind ourselves that the brain is a delicately adjustedorgan, which very easily gets disturbed, and that the best of us areliable to become the victims of absurd illusion if we habitually allowour imaginations to be overheated, whether by furious passion or byexcessive indulgence in the pleasures of day-dreaming, or in theintoxicating mysteries of spiritualist _séances_. But if we take care tokeep our heads cool and avoid unhealthy degrees of mental excitement, weneed not be very anxious on the ground of our liability to this kind oferror. As I have tried to show, our most frequent illusions arenecessarily connected with something exceptional, either in theorganism or in the environment. That is to say, it is of the nature ofillusion in healthy conditions of body and mind to be something veryoccasional and relatively unimportant. Our perceptions may be regardedas the reaction of the mind on the impressions borne in from theexternal world, or as a process of adjustment of internal mentalrelations to external physical relations. If this process is, in themain, a right one, we need not greatly trouble, because it is notinvariably so. We should accept the occasional failure of theintellectual mechanism as an inseparable accompaniment of its generalefficiency. To this it must be added that many of the illusions described above canhardly be called cases of non-adaptation at all, since they have norelation to the practical needs of life, and consequently are, in ageneral way, unattended to. In other cases, again, namely, where theprecise nature of a present sensation, being practically an unimportantmatter, is usually unattended to, as in the instantaneous recognition ofobjects by the eye under changes of illumination, etc. , the illusion israther a part of the process of adaptation, since it is much moreimportant to recognize the permanent object signified by the sensationthan the precise nature of the present sensational "sign" itself. Finally, it should never be forgotten that in normal states of mindthere is always the possibility of rectifying an illusion. Whatdistinguishes abnormal from normal mental life is the persistentoccupation of the mind by certain ideas, so that there is no room forthe salutary corrective effect of reflection on the actual impressionof the moment, by which we are wont to "orientate, " or take our bearingsas to the position of things about us. In sleep, and in certainartificially produced states, much the same thing presents itself. Images become realities just because they are not instantly recognizedas such by a reference to the actual surroundings of the moment. But innormal waking life this power of correction remains with us. We may notexercise it, it is true, and thus the illusion will tend to become moreor less persistent and recurring; for the same law applies to true andto false perception: repetition makes the process easier. But if we onlychoose to exert ourselves, we can always keep our illusions in a nascentor imperfectly developed stage. This applies not only to thosehalf-illusions into which we voluntarily fall, but also to the moreirresistible passive illusions, and those arising from an over-excitedimagination. Even persons subject to hallucinations, like Nicolai ofBerlin, learn to recognize the unreal character of these phantasms. Onthis point the following bit of autobiography from the pen of Coleridgethrows an interesting light. "A lady (he writes) once asked me if Ibelieved in ghosts and apparitions. I answered with truth andsimplicity, No, madam, I have seen far too many myself. "[68] Howeverirresistible our sense-illusions may be, so long as we are under thesway of particular impressions or mental images, we can, when resolvedto do so, undeceive ourselves by carefully attending to the actualstate of things about us. And in many cases, when once the correction ismade, the illusion seems an impossibility. By no effort of imaginationare we able to throw ourselves back into the illusory mental condition. So long as this power of dispelling the illusion remains with us, weneed not be alarmed at the number and variety of the momentarymisapprehensions to which we are liable. CHAPTER VII. DREAMS. The phenomena of dreams may well seem at first sight to form a world oftheir own, having no discoverable links of connection with the otherfacts of human experience. First of all, there is the mystery of sleep, which quietly shuts all the avenues of sense and so isolates the mindfrom contact with the world outside. To gaze at the motionless face of asleeper temporarily rapt from the life of sight, sound, andmovement--which, being common to all, binds us together in mutualrecognition and social action--has always something awe-inspiring. Thisexternal inaction, this torpor of sense and muscle, how unlike to thefamiliar waking life, with its quick responsiveness and its overflowingenergy! And then, if we look at dreams from the inside, we seem to findbut the reverse face of the mystery. How inexpressibly strange does thelate night-dream seem to a person on waking! He feels he has been seeingand hearing things no less real than those of waking life; but thingswhich belong to an unfamiliar world, an order of sights and a sequenceof events quite unlike those of waking experience; and he asks himselfin his perplexity where that once-visited region really lies, or by whatmagic power it was suddenly and for a moment created for his vision. Intruth, the very name of dream suggests something remote and mysterious, and when we want to characterize some impression or scene which by itspassing strangeness filled us with wonder, we naturally call itdream-like. _Theories of Dreams. _ The earliest theories respecting dreams illustrate very clearly thisperception of the remoteness of dream-life from waking experience. Bythe simple mind of primitive man this dream-world is regarded as similarin its nature or structure to our common world, only lying remote fromthis. The savage conceives that when he falls asleep, his second selfleaves his familiar body and journeys forth to unfamiliar regions, whereit meets the departed second selves of his dead ancestors, and so on. From this point of view, the experience of the night, though equal inreality to that of the day, is passed in a wholly disconnectedregion. [69] A second and more thoughtful view of dreams, marking a higher grade ofintellectual culture, is that these visions of the night are symbolicpictures unfolded to the inner eye of the soul by some supernaturalbeing. The dream-experience is now, in a sense, less real than it wasbefore, since the phantasms that wear the guise of objective realitiesare simply images spread out to the spirit's gaze, or the directutterance of a divine message. Still, this mysterious contact of themind with the supernatural is regarded as a fact, and so the dreamassumes the appearance of a higher order of experience. Its one point ofattachment to the experience of waking life lies in its symbolicfunction; for the common form which this supernatural view assumes isthat the dream is a dim prevision of coming events. Artemidorus, thegreat authority on dream interpretation (_oneirocritics_) for theancient world, actually defines a dream as "a motion or fiction of thesoul in a diverse form signifying either good or evil to come;" and evena logician like Porphyry ascribes dreams to the influence of a gooddemon, who thereby warns us of the evils which another and bad demon ispreparing for us. The same mode of viewing dreams is quite commonto-day, and many who pride themselves on a certain intellectual culture, and who imagine themselves to be free from the weakness of superstition, are apt to talk of dreams as of something mysterious, if not distinctlyominous. Nor is it surprising that phenomena which at first sight lookso wild and lawless, should still pass for miraculous interruptions ofthe natural order of events. [70] Yet, in spite of this obvious and impressive element of the mysteriousin dream-life, the scientific impulse to illuminate the less known bythe better known has long since begun to play on this obscure subject. Even in the ancient world a writer might here and there be found, likeDemocritus or Aristotle, who was bold enough to put forward a naturaland physical explanation of dreams. But it has been the work of modernscience to provide something like an approximate solution of theproblem. The careful study of mental life in its intimate union withbodily operations, and the comparison of dream-combinations with otherproducts of the imagination, normal as well as morbid, have graduallyhelped to dissolve a good part of the mystery which once hung like anopaque mist about the subject. In this way, our dream-operations havebeen found to have a much closer connection with our waking experiencesthan could be supposed on a superficial view. The materials of ourdreams are seen, when closely examined, to be drawn from our wakingexperience. Our waking consciousness acts in numberless ways on ourdreams, and these again in unsuspected ways influence our waking mentallife. [71] Not only so, it is found that the quaint chaotic play ofimages in dreams illustrates mental processes and laws which aredistinctly observable in waking thought. Thus, for example, the apparentobjective reality of these visions has been accounted for, without theneed of resorting to any supernatural agency, in the light of a vastassemblage of facts gathered from the by-ways, so to speak, of wakingmental life. I need hardly add that I refer to the illusions of sensedealt with in the foregoing chapters. Dreams are to a large extent the semblance of external perceptions. Other psychical phenomena, as self-reflection, emotional activity, andso on, appear in dream-life, but they do so in close connection withthese quasi-perceptions. The name "vision, " given by old writers todreams, sufficiently points out this close affinity of the mentalphenomena to sense-perception; and so far as science is concerned, theymust be regarded as a peculiar variety of sense-illusion. Hence theappropriateness of studying them in close connection with the illusionsof perception of the waking state. Though marked off by the presence ofvery exceptional physiological conditions, they are largely intelligibleby help of these physiological and psychological principles which wehave just been considering. _The State of Sleep. _ The physiological explanation of dreams must, it is plain, set out withan account of the condition of the organism known as sleep. While thereis here much that is uncertain, there are some things which are fairlywell known. Recent physiological observation has gone to prove thatduring sleep all the activities of the organism are appreciably lowered. Thus, for example, according to Testa, the pulse falls by aboutone-fifth. This lowering of the organic functions appears, underordinary circumstances, to increase towards midnight, after which thereis a gradual rising. The nervous system shares in this general depression of the vitalactivities. The circulation being slower, the process of reparation andnutrition of the nerves is retarded, and so their degree of excitabilitydiminished. This is clearly seen in the condition of the peripheralregions of the nervous system, including the sense-organs, which appearto be but very slightly acted on by their customary stimuli. The nervous centres must participate in this lethargy of the system. Inother words, the activity of the central substance is lowered, and theresult of this is plainly seen in what is usually thought of as thecharacteristic feature of sleep, namely, a transition from vigorousmental activity or intense and clear consciousness, to comparativeinactivity or faint and obscure consciousness. The cause of thiscondition of the centres is supposed to be the same as that of thetorpidity of all the other organs in sleep, namely, the retardation ofthe circulation. But, though there is no doubt as to this, the questionof the proximate physiological conditions of sleep is still far frombeing settled. Whether during sleep the blood-vessels of the brain arefuller or less full than during waking, is still a moot point. Also thequalitative condition of the blood in the cerebral vessels is still amatter of discussion. [72] Since the effect of sleep is to lower central activity, the questionnaturally occurs whether the nervous centres are ever rendered inactiveto such an extent as to interrupt the continuity of our conscious life. This question has been discussed from the point of view of themetaphysician, of the psychologist, and of the physiologist, and in nocase is perfect unanimity to be found. The metaphysical question, whether the soul as a spiritual substance is capable of being whollyinactive, or whether it is not in what seem the moments of profoundestunconsciousness partially awake--the question so warmly discussed by theCartesians, Leibnitz, etc. --need not detain us here. Of more interest to us are the psychological and the physiologicaldiscussions. The former seeks to settle the question by help ofintrospection and memory. On the one side, it is urged against thetheory of unbroken mental activity, that we remember so little of thelowered consciousness of sleep. [73] To this it is replied that ourforgetfulness of the contents of dream-consciousness, even if this wereunbroken, would be fully accounted for by the great dissimilaritybetween dreaming and waking mental life. It is urged, moreover, on thisside that a sudden rousing of a man from sleep always discovers him inthe act of dreaming, and that this goes to prove the uniform connectionof dreaming and sleeping. This argument, again, may be met by theassertion that our sense of the duration of our dreams is found to begrossly erroneous; that, owing to the rapid succession of the images, the _realization_ of which would involve a long duration, we enormouslyexaggerate the length of dreams in retrospection. [74] From this it isargued that the dream which is recalled on our being suddenly awakenedmay have had its whole course during the transition state of waking. Again, the fact that a man may resolve, on going to sleep, to wake at acertain hour, has often been cited in proof of the persistence of adegree of mental activity even in perfectly sound sleep. The force ofthis consideration, however, has been explained away by saying that theanticipation of rising at an unusual hour necessarily produces a slightamount of mental disquietude, which is quite sufficient to prevent soundsleep, and therefore to expose the sleeper to the rousing action offaint external stimuli. While the purely psychological method is thus wholly inadequate to solvethe question, physiological reasoning appears also to be not perfectlyconclusive. Many physiologists, not unnaturally desirous of upsettingwhat they regard as a gratuitous metaphysical hypothesis, havepronounced in favour of an absolutely dreamless or unconscious sleep. From the physiological point of view, there is no mystery in a totallysuspended mental activity. On the other hand, there is much to be saidon the opposite side, and perhaps it may be contended that the purelyphysiological evidence rather points to the conclusion that centralactivity, however diminished during sleep, always retains a minimumdegree of intensity. At least, one would be disposed to argue in thisway from the analogy of the condition of the other functions of theorganism during sleep. Possibly this modicum of positive evidence maymore than outweigh any slight presumption against the doctrine ofunbroken mental activity drawn from the negative circumstance that weremember so little of our dream-life. [75] Such being the state of physiological knowledge respecting theimmediate conditions of sleep, we cannot look for any certaininformation on the nature of that residual mode of cerebral activitywhich manifests itself subjectively in dreams. It is evident, indeed, that this question can only be fully answered when the condition of thebrain as a whole during sleep is understood. Meanwhile we must becontent with vague hypotheses. It may be said, for one thing, that during sleep the nervous substanceas a whole is less irritable than during waking hours. That is to say, agreater amount of stimulus is needed to produce any consciousresult. [76] This appears plainly enough in the case of the peripheralsense-organs. Although these are not, as it is often supposed, whollyinactive during sleep, they certainly require a more potent externalstimulus to rouse them to action. And what applies to the peripheralregions applies to the centres. In truth, it is clearly impossible todistinguish between the diminished irritability of the peripheral andthat of the central structures. At first sight it seems contradictory to the above to say that stimuliwhich have little effect on the centres of consciousness during wakinglife produce an appreciable result in sleep. Nevertheless, it will befound that this is the case. Thus organic processes which scarcely makethemselves known to the mind in a waking state, may be shown to be theoriginators of many of our dreams. This fact can only be explained onthe physical side by saying that the special cerebral activitiesengaged in an act of attention are greatly liberated during sleep by thecomparative quiescence of the external senses. These activities, byco-operating with the faint results of the stimuli coming from theinternal organs, serve very materially to increase their effect. Finally, it is to be observed that, while the centres thus respond withdiminished energy to peripheral stimuli, external and internal, theyundergo a direct, or "automatic, " mode of excitation, being roused intoactivity independently of an incoming nervous impulse. This automaticstimulation has been plausibly referred to the action of the products ofdecomposition accumulating in the cerebral blood-vessels. [77] It ispossible that there is something in the nature of this stimulation toaccount for the force and vividness of its conscious results, that is tosay, of dreams. _The Dream State. _ Let us now turn to the psychic side of these conditions, that is to say, to the general character of the mental states known as dreams. It isplain that the closing of the avenues of the external senses, which isthe accompaniment of sleep, will make an immense difference in themental events of the time. Instead of drawing its knowledge fromwithout, noting its bearings in relation to the environment, the mindwill now be given over to the play of internal imagination. The activityof fancy will, it is plain, be unrestricted by collision with externalfact. The internal mental life will expand in free picturesquemovement. To say that in sleep the mind is given over to its own imaginings, is tosay that the mental life in these circumstances will reflect theindividual temperament and mental history. For the play of imaginationat any time follows the lines of our past experience more closely thanwould at first appear, and being coloured with emotion, will reflect thepredominant emotional impulses of the individual mind. Hence the sayingof Heraclitus, that, while in waking we all have a common world, insleep we have each a world of our own. This play of imagination in sleep is furthered by the peculiar attitudeof attention. When asleep the voluntary guidance of attention ceases;its direction is to a large extent determined by the contents of themind at the moment. Instead of holding the images and ideas, andcombining them according to some rational end, the attention relaxes itsenergies and succumbs to the force of imagination. And thus, in sleep, just as in the condition of reverie or day-dreaming, there is anabandonment of the fancy to its own wild ways. It follows that the dream-state will not appear to the mind as one offancy, but as one of actual perception, and of contact with presentreality. Dreams are clearly illusory, and, unlike the illusions ofwaking life, are complete and persistent. [78] And the reason of thisought now to be clear. First of all, the mind during sleep wants what M. Taine calls the corrective of a present sensation. When awake underordinary circumstances, any momentary illusion is at once set right by anew act of orientation. The superior vividness of the externalimpression cannot leave us in any doubt, when calm and self-possessed, whether our mental images answer to present realities or not. On theother hand, when asleep, this reference to a fixed objective standard isclearly impossible. Secondly, we may fairly argue that the mental imagesof sleep approximate in character to external impressions. This they doto some extent in point of intensity, for, in spite of the diminishedexcitability of the centres, the mode of stimulation which occurs insleep may, as I have hinted, involve an energetic cerebral action. And, however this be, it is plain that the image will gain a preternaturalforce through the greatly narrowed range of attention. When the mind ofthe sleeper is wholly possessed by an image or group of images, and theattention kept tied down to these, there is a maximum reinforcement ofthe images. But this is not all. When the attention is thus held captiveby the image, it approximates in character to an external impression inanother way. In our waking state, when our powers of volition areintact, the external impression is characterized by its fixity or itsobdurate resistance to our wishes. On the other hand, the mental imageis fluent, accommodating, and disappears and reappears according to thedirection of our volitions. In sleep, through the suspension of thehigher voluntary power of attention, the mental image seems to lord itover our minds just as the actual impression of waking life. This much may suffice, perhaps, by way of a general description of thesleeping and dreaming state. Other points will make themselves knownafter we have studied the contents and structure of dreams in detail. Dreams are commonly classified (_e. G. _ by Wundt) with hallucinations, and this rightly, since, as their common appellation of "vision"suggests, they are for the most part the semblance of percepts in theabsence of external impressions. At the same time, recent research goesto show that in many dreams something answering to the "externalimpression" in waking perception is the starting-point. Consequently, inorder to be as accurate as possible, I shall divide dreams intoillusions (in the narrow sense) and hallucinations. _Dream-Illusions. _ By dream-illusions I mean those dreams which set out from someperipheral nervous stimulation, internal or external. That the organicprocesses of digestion, respiration, etc. , act as stimuli to the centresin sleep is well known. Thus, David Hartley assigns as the second greatsource of dreams "states of the body. "[79] But it is not so well knownto what an extent our dreams may be influenced by stimuli acting on theexterior sense-organs. Let us first glance at the action of suchexternal stimuli. _Action of External Stimuli. _ During sleep the eyes are closed, and consequently the action ofexternal light on the retina impeded. Yet it is found that even underthese circumstances any very bright light suddenly introduced is capableof stimulating the optic fibres, and of affecting consciousness. Themost common form of this is the effect of bright moonlight, and of theearly sun's rays. Krauss tells a funny story of his having once, whentwenty-six years old, caught himself, on waking, in the act ofstretching out his arms towards what his dream-fancy had pictured as theimage of his mistress. When fully awake, this image resolved itself intothe full moon. [80] It is not improbable, as Radestock remarks, that therays of the sun or moon are answerable for many of the dreams ofcelestial glory which persons of a highly religious temperament are saidto experience. External sounds, when not sufficient to rouse the sleeper, easilyincorporate themselves into his dreams. The ticking of a watch, thestroke of a clock, the hum of an insect, the song of a bird, the patterof rain, are common stimuli to the dream-phantasy. M. Alf. Maury tellsus, in his interesting account of the series of experiments to which hesubmitted himself in order to ascertain the result of externalstimulation on the mind during sleep, that when a pair of tweezers wasmade to vibrate near his ear, he dreamt of bells, the tocsin, and theevents of June, 1848. [81] Most of us, probably, have gone through theexperience of impolitely falling asleep when some one was reading to us, and of having dream-images suggested by the sounds that were stillindistinctly heard. Scherner gives an amusing case of a youth who waspermitted to whisper his name into the ear of his obdurate mistress, the consequence of which was that the lady contracted a habit ofdreaming about him, which led to a felicitous change of feeling on herpart. [82] The two lower senses, smell and taste, seem to play a less-importantpart in the production of dream-illusions. Radestock says that the odourof flowers in a room easily leads to visual images of hot-houses, perfumery shops, and so on; and it is probable that the contents of themouth may occasionally act as a stimulus to the organ of taste, and sogive rise to corresponding dreams. As Radestock observes, these lowersensations do not commonly make known their quality to the sleeper'smind. They become transformed at once into visual, instead of intoolfactory or gustatory percepts. That is to say, the dreamer does notimagine himself smelling or tasting, but seeing an object. The contact of objects with the tactual organ is one of the bestrecognized causes of dreams. M. Maury found that when his lips weretickled, his dream-fancy interpreted the impression as of a pitchplaster being torn off his face. An unusual pressure on any part of thebody, as, for example, from contact with a fellow-sleeper, is known togive rise to a well-marked variety of dream. Our own limbs may evenappear as foreign bodies to our dream-imagination, when through pressurethey become partly paralyzed. Thus, on one occasion, I awoke from amiserable dream, in which I felt sure I was grasping somebody's hand inbed, and I was racked by terrifying conjectures as to who it might be. When fully awake, I discovered that I had been lying on my right side, and clasping the wrist of the right arm (which had been renderedinsensible by the pressure of the body) with the left hand. In close connection with these stimuli of pressure are those of muscularmovement, whether unimpeded or impeded. We need not enter into thedifficult question how far the "muscular sense" is connected with theactivity of the motor nerves, and how far with sensory fibres attachedto the muscular or the adjacent tissues. Suffice it to say that anactual movement, a resistance to an attempted movement, or a meredisposition to movement, whether consequent on a surplus of motor energyor on a sensation of discomfort or fatigue in the part to be moved, somehow or other makes itself known to our minds, even when we aredeprived of the assistance of vision. And these feelings of movement, impeded or unimpeded, are common initial impulses in ourdream-experiences. It is quite a mistake to suppose that dreams arebuilt up out of the purely passive sensations of sight and hearing. Aclose observation will show that in nearly every dream we imagineourselves either moving among the objects we perceive or striving tomove when some weighty obstacle obstructs us. All of us are familiarwith the common forms of nightmare, in which we strive hopelessly toflee from some menacing evil, and this dream-experience, it may bepresumed, frequently comes from a feeling of strain in the muscles, dueto an awkward disposition of the limbs during sleep. The commondream-illusion of falling down a vast abyss is plausibly referred byWundt to an involuntary extension of the foot of the sleeper. _Action of Internal Stimuli. _ Let us now pass from the action of stimuli lying outside the organism, to that of stimuli lying within the peripheral regions of thesense-organs. I have already spoken of the influence of subjectivesensations of sight, hearing, etc. , on the illusions of waking life, andit is now to be added that these sensations play an important part inour dream-life. Johannes Müller lays great prominence on the part takenby ocular spectra in the production of dreams. As he observes, theapparent rays of light, light-patches, mists of light, and so on, due tochanges of blood-pressure in the retina, only manifest themselvesclearly when the eyes are closed and the more powerful effect of theexternal stimulus cut off. These subjective spectra come into prominencein the sleepy condition, giving rise to what M. Maury calls"hallucinations hypnagogiques, " and which he regards (after Gruithuisen)as the chaos out of which the dream-cosmos is evolved. [83] They arepretty certainly the starting-point in those picturesque dreams in whichfigure a number of bright objects, such as beautiful birds, butterflies, flowers, or angels. That the visual images of our sleep do often involve the peripheralregions of the organ of sight, seems to be proved by the singular factthat they sometimes persist after waking. Spinoza and Jean Paul Richterboth experienced this survival of dream-images. Still more pertinent isthe fact that the effects of retinal fatigue are producible bydream-images. The physiologist Gruithuisen had a dream, in which theprincipal feature was a violet flame, and which left behind it, _afterwaking_, for an appreciable duration, a complementary image of a yellowspot. [84] Subjective auditory sensations appear to be much less frequent causes ofdream-illusions than corresponding visual sensations. Yet the rushing, roaring sound caused by the circulation of the blood in the ear is, probably, a not uncommon starting-point in dreams. With respect tosubjective sensations of smell and taste, there is little to be said. Onthe other hand, subjective sensations due to varying conditions in theskin are a very frequent exciting cause of dreams. Variations in thestate of tension of the skin, brought about by alteration of position, changes in the character of the circulation, the irradiation of heat tothe skin or the loss of the same, chemical changes, --these are known togive rise to a number of familiar sensations, including those oftickling, itching, burning, creeping, and so on; and the effects ofthese sensations are distinctly traceable in our dreams. For example, the exposure of a part of the body through a loss of the bed-clothes isa frequent excitant of distressing dreams. A cold foot suggests that thesleeper is walking over snow or ice. On the other hand, if the cold foothappens to touch a warm part of the body, the dream-fancy constructsimages of walking on burning lava, and so on. These sensations of the skin naturally conduct us to the organicsensations as a whole; that is to say, the feelings connected with thevarying condition of the bodily organs. These include the feelings whicharise in connection with the processes of digestion, respiration, andcirculation, and the condition of various organs according to theirstate of nutrition, etc. During our waking life these organic feelingscoalesce for the most part, forming as the "vital sense" an obscurebackground for our clear discriminative consciousness, and only comeforward into this region when very exceptional in character, as whenrespiration or digestion is impeded, or when we make a special effort ofattention to single them out. [85] When we are asleep, however, and theavenues of external perception are closed, they assume greaterprominence and distinctness. The centres, no longer called upon to reacton stimuli coming from without the organism, are free to react onstimuli coming from its hidden recesses. So important a part, indeed, dothese organic feelings take in the dream-drama, that some writers aredisposed to regard them as the great, if not the exclusive, cause ofdreams. Thus, Schopenhauer held that the excitants of dreams areimpressions received from the internal regions of the organism throughthe sympathetic nervous system. [86] It is hardly necessary, perhaps, to give many illustrations of theeffect of such organic sensations on our dreams. Among the most commonprovocatives of dreams are sensations connected with a difficulty inbreathing, due to the closeness of the air or to the pressure of thebed-clothes on the mouth. J. Börner investigated the influence of thesecircumstances by covering with the bed-clothes the mouth and a part ofthe nostrils of persons who were sound asleep. This was followed by aprotraction of the act of breathing, a reddening of the face, efforts tothrow off the clothes, etc. On being roused, the sleeper testified thathe had experienced a nightmare, in which a horrid animal seemed to beweighing him down. [87] Irregularity of the heart's action is also afrequent cause of dreams. It is not improbable that the familiardream-experience of flying arises from disturbances of the respiratoryand circulatory movements. Again, the effects of indigestion, and more particularly stomachicderangement, on dreams are too well known to require illustration. Itmay be enough to allude to the famous dream which Hood traces to anexcessive indulgence at supper. It is known that the varying conditionof the organs of secretion influences our dream-fancy in a number ofways. Finally, it is to be observed that an injury done to any part of theorganism is apt to give rise to appropriate dream-images. In this way, very slight disturbances which would hardly affect waking consciousnessmay make themselves felt during sleep. Thus, for example, an incipienttoothache has been known to suggest that the teeth are beingextracted. [88] It is worth observing that the interpretation of these various orders ofsensations by the imagination of the dreamer takes very different formsaccording to the person's character, previous experience, rulingemotions, and so on. This is what is meant by saying that during sleepevery man has a world of his own, whereas, when awake, he shares in thecommon world of perception. _Dream-Exaggeration. _ It is to be noticed, further, that this interpretation of sensationduring sleep is uniformly a process of exaggeration. [89] The excitingcauses of the feeling of discomfort, for example, are always absurdlymagnified. The reason of this seems to be that, owing to the conditionof the mind during sleep, the nature of the sensation is not clearlyrecognizable. Even in the case of familiar external impressions, such asthe sound of the striking of a clock, there appears to be wanting thatsimple process of reaction by which, in a waking condition of theattention, a sense-impression is instantly discriminated and classed. Insleep, as in the artificially induced hypnotic condition, the slighterdifferences of quality among sensations are not clearly recognized. Theactivity of the higher centres, which are concerned in the finerprocesses of discrimination and classification, being greatly reduced, the impression may be said to come before consciousness as somethingnovel and unfamiliar. And just as we saw that in waking life novelsensations agitate the mind, and so lead to an exaggerated mode ofinterpretation; so here we see that what is unfamiliar disturbs themind, rendering it incapable of calm attention and just interpretation. This failure to recognize the real nature of an impression is seen mostconspicuously in the case of the organic sensations. As I have remarked, these constitute for the most part, in waking life, an undiscriminatedmass of obscure feeling, of which we are only conscious as the mentaltone of the hour. And in the few instances in which we do attend to themseparately, whether through their exceptional intensity or inconsequence of an extraordinary effort of discriminative attention, wecan only be said to perceive them, that is, recognize their localorigin, very vaguely. Hence, when asleep, these sensations get veryoddly misinterpreted. The localization of a bodily sensation in waking life means thecombination of a tactual and a visual image with the sensation. Thus, myrecognition of a twinge of toothache as coming from a certain tooth, involves representations of the active and passive sensations whichtouching and looking at the tooth would yield me. That is to say, thefeeling instantly calls up a compound mental image exactly answering toa visual percept. This holds good in dream-interpretation too; theinterpretation is effected by means of a visual image. But since thefeeling is only very vaguely recognized, this visual image does notanswer to the bodily part concerned. Instead of this, the fancy of thedreamer constructs some visual image which bears a vague resemblance tothe proper one, and is generally, if not always, an exaggeration of thisin point of extensive magnitude, etc. For example, a sensation arisingfrom pressure on the bladder, being dimly connected with the presence ofa fluid, calls up an image of a flood, and so on. This mode of dream-interpretation has by some writers been erected intothe typical mode, under the name of dream-symbolism. Thus Scherner, inhis interesting though somewhat fanciful work, _Das Leben des Traumes_, contends that the various regions of the body regularly disclosethemselves to the dream-fancy under the symbol of a building or group ofbuildings; a pain in the head calling up, for example, the image ofspiders on the ceiling, intestinal sensations exciting an image of anarrow alley, and so on. Such theories are clearly an exaggeration ofthe fact that the localization of our bodily sensations during sleep isnecessarily imperfect. [90] In many cases the image called up bears on its objective side nodiscoverable resemblance to that of the bodily region or the excitingcause of the sensation. Here the explanation must be looked for in thesubjective side of the sensation and mental image, that is to say, intheir emotional quality, as pleasurable or painful, distressing, quieting, etc. It is to be observed, indeed, that in natural sleep, asin the condition known as hypnotism, while differences of specificquality in the sense-impressions are lost, the broad difference of thepleasurable and the painful is never lost. It is, in fact, thesubjective emotional side of the sensation that uniformly forces itselfinto consciousness. This being so, it follows that, speaking generally, the sensations of sleep, both external and internal, or organic, will beinterpreted by what G. H. Lewes has called "an analogy of feeling;" thatis to say, by means of a mental image having some kindred emotionalcharacter or colouring. Now, the analogy between the higher emotional and the bodily states is avery close one. A sensation of obstruction in breathing has its exactanalogue in a state of mental embarrassment, a sensation of itching itscounterpart in mental impatience, and so on. And since these emotionalexperiences are deeper and fuller than the sensations, the tendency toexaggerate the nature and causes of these last would naturally lead toan interpretation of them by help of these experiences. In addition tothis, the predominance of visual imagery in sleep would aid thistransformation of a bodily sensation into an emotional experience, sincevisual perceptions have, as their accompaniments of pleasure and pain, not sensations, but emotions. [91] Since in this vague interpretation of bodily sensation the actualimpression is obscured, and not taken up as an integral part into thepercept, it is evident that we cannot, strictly speaking, call theprocess an imitation of an act of perception, that is to say, anillusion. And since, moreover, the visual image by which the sensationis thus displaced appears as a present object, it would, of course, beallowable to speak of this as an hallucination. This substitution of amore or less analogous visual image for that appropriate to thesensation forms, indeed, a transition from dream-illusion, properly socalled, to dream-hallucination. _Dream-Hallucinations. _ On the physical side, these hallucinations answer to cerebralexcitations which are central or automatic, not depending on movementstransmitted from the periphery of the nervous system. Of thesestimulations some appear to be direct, and due to unknown influencesexerted by the state of nutrition of the cerebral elements, or theaction of the contents of the blood-vessels on these elements. _Effects of Direct Central Stimulation. _ That such action does prompt a large number of dream-images may beregarded as fairly certain. First of all, it seems impossible to accountfor all the images of dream-fancy as secondary phenomena connected bylinks of association with the foregoing classes of sensation. Howeverfine and invisible many of the threads which hold together our ideas maybe, they will hardly explain the profusion and picturesque variety ofdream-imagery. Secondly, we are able in certain cases to infer with afair amount of certainty that a dream-image is due to such centralstimulation. The common occurrence that we dream of the more stirringevents, the anxieties and enjoyments of the preceding day, appears toshow that when the cerebral elements are predisposed to a certain kindof activity, as they are after having been engaged for some time in thisparticular work, they are liable to be excited by some stimulus broughtdirectly to bear on them during sleep. And if this is so, it is notimprobable that many of the apparently forgotten images of persons andplaces which return with such vividness in dreams are excited by a modeof stimulation which is for the greater part confined to sleep. I say"for the greater part, " because even in our indolent, listless momentsof waking existence such seemingly forgotten ideas sometimes return asthough by a spontaneous movement of their own and by no discoverableplay of association. It may be well to add that this immediate revival of impressionspreviously received by the brain includes not only the actualperceptions of waking life, but also the ideas derived from others, theideal fancies supplied by works of fiction, and even the images whichour unaided waking fancy is wont to shape for itself. Our dailyconjectures as to the future, the communications to us by others oftheir thoughts, hopes, and fears, --these give rise to numberless vaguefugitive images, any one of which may become distinctly revived insleep. [92] This throws light on the curious fact that we often dream ofexperiences and events quite unlike those of our individual life. Thus, for example, the common construction by the dream-fancy of theexperience of flight in mid-air, and the creation of those weird formswhich the terror of a nightmare is wont to bring in its train, seem topoint to the past action of waking fancy. To imagine one's self flyingwhen looking at a bird is probably a common action with all persons, atleast in their earlier years, and images of preternaturally horriblebeings are apt to be supplied to most of us some time during life bynurses or by books. _Indirect Central Stimulation. _ Besides these direct central stimulations, there are others which, incontradistinction, may be called indirect, depending on some previousexcitation. These are, no doubt, the conditions of a very large numberof our dream-images. There must, of course, be some primary cerebralexcitation, whether that of a present peripheral stimulation, or thatwhich has been termed central and spontaneous; but when once this firstlink of the imaginative chain is supplied, other links may be added inlarge numbers through the operation of the forces of association. Onemay, indeed, safely say that the large proportion of the contents ofevery dream arise in this way. The very simplest type of dream excited by a present sensation containsthese elements. To take an example, I once dreamt, as a consequence ofthe loud barking of a dog, that a dog approached me when lying down, andbegan to lick my face. Here the play of the associative forces wasapparent: a mere sensation of sound called up the appropriate visualimage, this again the representation of a characteristic action, and soon. So it is with the dreams whose first impulse is some central orspontaneous excitation. A momentary sight of a face or even the mentionof a name during the preceding day may give the start to dream-activity;but all subsequent members of the series of images owe their revival toa tension, so to speak, in the fine threads which bind together, in socomplicated a way, our impressions and ideas. Among the psychic accompaniments of these central excitations visualimages, as already hinted, fill the most conspicuous place. Evenauditory images, though by no means absent, are much less numerous thanvisual. Indeed, when there are the conditions for the former, itsometimes happens that the auditory effect transforms itself into avisual effect. An illustration of this occurred in my own experience. Trying to fall asleep by means of the well-known device of counting, Isuddenly found myself losing my hold on the faint auditory effects, myimagination transforming them into a visual spectacle, under the form ofa path of light stretching away from me, in which the numbers appearedunder the grotesque form of visible objects, tumbling along in gloriousconfusion. Next to these visual phantasms, certain motor hallucinations seem to bemost prominent in dreams. By a motor hallucination, I mean the illusionthat we are actually moving when there is no peripheral excitation ofthe motor organ. Just as the centres concerned in passive sensation aresusceptible of central stimulation, so are the centres concerned inmuscular sensation. A mere impulse in the centres of motor innervation(if we assume these to be the central seat of the muscular feelings) maysuffice to give rise to a complete representation of a fully executedmovement. And thus in our sleep we seem to walk, ride, float, or fly. The most common form of motor hallucination is probably the vocal. Inthe social encounters which make up so much of our sleep-experience, weare wont to be very talkative. Now, perhaps, we find ourselves zealouslyadvocating some cause, now very fierce in denunciation, now very amusingin witty repartee, and so on. This imagination of ourselves as speaking, as distinguished from that of hearing others talking, must, it is clear, involve the excitation of the structures engaged in the production ofthe muscular feelings which accompany vocal action, as much as, if notmore than, the auditory centres. And the frequency of this kind ofdream-experience may be explained, like that of visual imagery, by thehabits of waking life. The speech impulse is one of the most deeplyrooted of all our impulses, and one which has been most frequentlyexercised in waking life. _Combination of Dream-Elements. _ It is commonly said that dreams are a grotesque dissolution of allorder, a very chaos and whirl of images without any discoverableconnection. On the other hand, a few writers claim for the mind in sleepa power of arranging and grouping its incongruous elements in definiteand even life-like pictures. Each of these views is correct withincertain limits; that is to say, there are dreams in which the strangestdisorder seems to prevail, and others in which one detects the action ofa central control. Yet, speaking generally, sequences of dream-imageswill be found to be determined by certain circumstances and laws, and sofar not to be haphazard or wholly chaotic. We have now to inquire intothe laws of these successions; and, first of all, we may ask how far theknown laws of association, together with the peculiar conditions of thesleeping state, are able to account for the various modes ofdream-combination. We have already regarded mental association asfurnishing a large additional store of dream-imagery; we have now toconsider it as explaining the sequences and concatenations of ourdream-elements. _Incoherence of Dreams. _ First of all, then, let us look at the chaotic and apparently lawlessside of dreaming, and see whether any clue is discoverable to the centreof this labyrinth. In the case of all the less elaborately ordereddreams, in which sights and sounds appear to succeed one another in thewildest dance (which class of dreams probably belongs to the deeperstages of sleep), the mind may with certainty be regarded as purelypassive, and the mode of sequence may be referred to the action ofassociation complicated by the ever-recurring introduction of newinitial impulses, both peripheral and central. These are the dreams inwhich we are conscious of being perfectly passive, either as spectatorsof a strange pageant, or as borne away by some apparently extraneousforce through a series of the most diverse experiences. The flux ofimages in these dreams is very much the same as that in certain wakingconditions, in which we relax attention, both external and internal, andyield ourselves wholly to the spontaneous play of memory and fancy. It is plain at a glance that the simultaneous concurrence of whollydisconnected initial impulses will serve to impress a measure ofdisconnectedness on our dream-images. From widely remote parts of theorganism there come impressions which excite each its peculiar visual orother image according as its local origin or its emotional tone is themore distinctly present to consciousness. Now it is a subjective ocularsensation suggesting a bouquet of lovely flowers, and close on its heelscomes an impression from the organs of digestion suggesting all mannerof obstacles, and so our dream-fancy plunges from a vision of flowers toone of dreadful demons. Let us now look at the way in which the laws of association working onthe incongruous elements thus cast up into our dream-consciousness, willserve to give a yet greater appearance of disorder and confusion to ourdream-combinations. According to these laws, any idea may, undercertain circumstances, call up another, if the corresponding impressionshave only once occurred together, or if the ideas have any degree ofresemblance, or, finally, if only they stand in marked contrast with oneanother. Any accidental coincidence of events, such as meeting a personat a particular foreign resort, and any insignificant resemblancebetween objects, sounds, etc. , may thus supply a path, so to speak, fromfact to dream-fancy. In our waking states these innumerable paths of association arepractically closed by the supreme energy of the coherent groups ofimpressions furnished us from the world without through our organs ofsense, and also by the volitional control of internal thought inobedience to the pressure of practical needs and desires. In dream-lifeboth of these influences are withdrawn, so that delicate threads ofassociation, which have no chance of exerting their pull, so to speak, in our waking states, now make known their hidden force. Little wonder, then, that the filaments which bind together these dream-successionsshould escape detection, since even in our waking thought we so oftenfail to see the connection which makes us pass in recollection from aname to a visible scene or perhaps to an emotional vibration. It is worth noting that the origin of an association is often to belooked for in one of those momentary half-conscious acts of wakingimagination to which reference has already been made. A friend, forexample, has been speaking to us of some common acquaintance, remarkingon his poor health. The language calls up, vaguely, a visualrepresentation of the person sinking in health and dying. Anassociation will thus be formed between this person and the idea ofdeath. A night or two after, the image of this person somehow recurs toour dream-fancy, and we straightway dream that we are looking at hiscorpse, watching his funeral, and so on. The links of the chain whichholds together these dream-images were really forged, in part, in ourwaking hours, though the process was so rapid as to escape ourattention. It may be added, that in many cases where a juxtaposition ofdream-images seems to have no basis in waking life, careful reflectionwill occasionally bring to light some actual conjunction of impressionsso momentary as to have faded from our recollection. We must remember, further, how great an apparent disorder will invadeour imaginative dream-life when the binding force of resemblance hasunchecked play. In waking thought we have to connect things according totheir essential resemblances, classifying objects and events forpurposes of knowledge or action, according to their widest or their mostimportant points of similarity. In sleep, on the contrary, the slightesttouch of resemblance may engage the mind and affect the direction offancy. In a sense we may be said, when dreaming, to discover mentalaffinities between impressions and feelings, including those subtlelinks of emotional analogy of which I have already spoken. This effectis well illustrated in a dream recorded by M. Maury, in which he passedfrom one set of images to another through some similarity of names, asthat between _corps_ and _cor_. Such a movement of fancy would, ofcourse, be prevented in full waking consciousness by a predominantattention to the meaning of the sounds. It will be possible, I think, after a habit of analyzing one's dreams inthe light of preceding experience has been formed, to discover in a goodproportion of cases some hidden force of association which drawstogether the seemingly fortuitous concourse of our dream-atoms. That weshould expect to do so in every case is unreasonable, since, owing tothe numberless fine ramifications which belong to our familiar images, many of the paths of association followed by our dream-fancy cannot beafterwards retraced. To illustrate the odd way in which our images get tumbled togetherthrough the action of occult association forces, I will record a dreamof my own. I fancied I was at the house of a distinguished literaryacquaintance, at her usual reception hour. I expected the friends I wasin the habit of meeting there. Instead of this, I saw a number ofcommonly dressed people having tea. My hostess came up and apologizedfor having asked me into this room. It was, she said, a tea-party whichshe prepared for poor people at sixpence a head. After puzzling overthis dream, I came to the conclusion that the missing link was a verbalone. A lady who is a connection of my friend, and bears the same name, assists her sister in a large kind of benevolent scheme. I may add thatI had not, so far as I could recollect, had occasion very recently tothink of this benevolent friend, but I had been thinking of my literaryfriend in connection with her anticipated return to town. In thus seeking to trace, amid the superficial chaos of dream-fancy, its hidden connections, I make no pretence to explain why in any givencase these particular paths of association should be followed, and moreparticularly why a slender thread of association should exert a pullwhere a stronger cord fails to do so. To account for this, it would benecessary to call in the physiological hypothesis that among the nervouselements connected with a particular element, _a_, already excited, some, as _m_ and _n_, are at the moment, owing to the state of theirnutrition or their surrounding influences, more powerfully predisposedto activity than other elements, as _b_ and _c_. The subject of association naturally conducts us to the second greatproblem in the theory of dreams--the explanation of the order in whichthe various images group themselves in all our more elaborate dreams. _Coherence of Dreams. _ A fully developed dream is a complex of many distinct illusorysense-presentations: in this respect it differs from the illusions ofnormal waking life, which are for the most part single and isolated. Andthis complex of quasi-presentations appears somehow or other to falltogether into one whole scene or series of events, which, though it maybe very incongruous and absurdly impossible from a waking point of view, nevertheless makes a single object for the dreamer's internal vision, and has a certain degree of artistic unity. This plastic force, whichselects and binds together our unconnected dream-images, has frequentlybeen referred to as a mysterious spiritual faculty, under the name of"creative fancy. " Thus Cudworth remarks, in his _Treatise concerningEternal and Immutable Morality_: "That dreams are many times begotten bythe phantastical power of the soul itself . .. Is evident from theorderly connection and coherence of imaginations which many times arecontinued in a long chain or series. " One may find a good deal ofmystical writing on the nature and activity of this faculty, especiallyin German literature. The explanation of this element of organic unityin dreams is, it may be safely said, the crux in the science of dreams. That the laws of psychology help us to understand the sequences ofdream-images, we have seen. What we have now to ask is whether theselaws throw any light on the orderly grouping of the elements so broughtup in consciousness in the form of a connected experience. It is to be remarked at the outset that a singular kind of unity issometimes given to our dream-combinations by a total or partialcoalescence of different images. The conditions of such coalescence havebeen referred to already. [93] Simultaneous impressions or images willalways tend to coalesce with a force which varies directly as the degreeof their similarity. Sometimes this coalescence is instantaneous and notmade known to consciousness. Thus, Radestock suggests that if the mindof the sleeper is simultaneously invaded by an unpleasant sensationarising out of some disturbance of the functions of the skin, and asubjective visual sensation, the resulting mental image may be acombination of the two, under the form of a caterpillar creeping overthe bodily surface. And the coalescence may even be prepared bysub-conscious operations of waking imagination. Thus, for example, Ionce spoke about the cheapness of hares to a member of my family, whosomewhat grimly suggested that they were London cats. I did not dwell onthe idea, but the following night I dreamt that I saw a big hybridcreature, half hare, half cat, sniffing about a cottage. As it stood onits hind legs and took a piece of food from a window-ledge, I becamesure that it was a cat. Here it is plain that the cynical observation ofmy relative had, at the moment, partially excited an image of thisfeline hare. In some dreams, again, we may become aware of the processof coalescence, as when persons who at one moment were seen to bedistinct appear to our dream-fancy to run together in some third person. A very similar kind of unification takes place between sequent imagesunder the form of transformation. When two images follow one anotherclosely, and have anything in common, they readily assume the form of atransmutation. There is a sort of overlapping of the mental images, andso an appearance of continuity produced in some respects analogous tothat which arises in the wheel-of-life (thaumatrope) class ofsense-illusions. This would seem to account for the odd transformationsof personality which not unfrequently occur in dreams, in which a personappears, by a kind of metempsychosis, to transfer his physical ego toanother, and in which the dreamer's own bodily phantom plays similarfreaks. And the same principle probably explains those dissolving-vieweffects which are so familiar an accompaniment of dream-scenery. [94] But passing from this exceptional kind of unity in dreams, let usinquire how the heterogeneous elements of our dream-fancy become orderedand arranged when they preserve their separate existence. If we lookclosely at the structure of our more finished dreams, we find that theappearance of harmony, connectedness, or order, may be given in one oftwo ways. There may, first of all, be a subjective harmony, the variousimages being held together by an emotional thread. Or there may, secondly, be an objective harmony, the parts of the dream, thoughanswering to no particular experiences of waking life, bearing a certainresemblance to our habitual modes of experience. Let us inquire into theway in which each kind of order is brought about. _Lyrical Element in Dreams. _ The only unity that belongs to many of our dreams is a subjectiveemotional unity. This is the basis of harmony in lyrical poetry, wherethe succession of images turns mainly on their emotional colouring. Thus, the images that float before the mind of the Poet Laureate, in his_In Memoriam_, clearly have their link of connection in their commonemotional tone, rather than in any logical continuity. Dreaming has beenlikened to poetic composition, and certainly many of our dreams arebuilt upon a groundwork of lyrical feeling. They might be marked off, perhaps, as our lyrical dreams. The way in which this emotional force acts in these cases has alreadybeen hinted at. We have seen that the analogy of feeling is a commonlink between dream-images. Now, if any shade of feeling becomes fixedand dominant in the mind, it will tend to control all the images of thetime, allowing certain congruous ones to enter, and excludingothers. [95] If, for example, a feeling of distress occupies the mind, distressing images will have the advantage in the struggle for existencewhich goes on in the world of mind as well as in that of matter. We maysay that attention, which is here wholly a passive process, iscontrolled by the emotion of the time, and bent in the direction ofcongruent or harmonious images. Now, a ground-tone of feeling of a certain complexion, answering to thesum of sensations arising in connection with the different organicprocesses of the time, is a very frequent foundation of ourdream-structure. So frequent is it, indeed, that one might almost saythere is no dream in which it is not one great determining factor. Theanalysis of a very large number of dreams has convinced me that tracesof this influence are discoverable in a great majority. I will give a simple illustration of this lyrical type of dream. Alittle girl of about four years and three-quarters went with her parentsto Switzerland. On their way she was taken to the cathedral atStrasburg, and saw the celebrated clock strike, and the figures of theApostles come out, etc. In Switzerland she stayed at Gimmelwald, nearMürren, opposite a fine mass of snowy mountains. One morning she toldher father that she had had "such a lovely dream. " She fancied she wason the snow-peaks with her nurse, and walked on to the sky. There cameout of the sky "such beautiful things, " just like the figures of theclock. This vision of celestial things was clearly due to the fact thatboth the clock and the snow-peaks touching the blue sky had powerfullyexcited her imagination, filling her with much the same kind of emotion, namely, wonder, admiration, and longing to reach an inaccessible height. Our feelings commonly have a gradual rise and fall, and the organicsensations which so often constitute the emotional basis of our lyricaldreams generally have stages of increasing intensity. Moreover, such apersistent ground-feeling becomes reinforced by the images which itsustains in consciousness. Hence a certain _crescendo_ character in ouremotional dreams, or a gradual rise to some culminating point or climax. This phase of dream can be illustrated from the experience of the samelittle girl. When just five years old, she was staying at Hampstead, near a church which struck the hours somewhat loudly. One morning sherelated the following dream to her father (I use her own language). Thebiggest bells in the world were ringing; when this was over the earthand houses began to tumble to pieces; all the seas, rivers, and pondsflowed together, and covered all the land with black water, as deep asin the sea where the ships sail; people were drowned; she herself flewabove the water, rising and falling, fearing to fall in; she then sawher mamma drowned, and at last flew home to tell her papa. The gradualincrease of alarm and distress expressed in this dream, having itsprobable cause in the cumulative effect of the disturbing sound of thechurch bells, must be patent to all. The following rather comical dream illustrates quite as clearly thegrowth of a feeling of irritation and vexation, probably connected withthe development of some slightly discomposing organic sensation. Idreamt I was unexpectedly called on to lecture to a class of youngwomen, on Herder. I began hesitatingly, with some vague generalitiesabout the Augustan age of German literature, referring to the threewell-known names of Lessing, Schiller, and Goethe. Immediately mysister, who suddenly appeared in the class, took me up, and said shethought there was a fourth distinguished name belonging to this period. I was annoyed at the interruption, but said, with a feeling of triumph, "I suppose you mean Wieland?" and then appealed to the class whetherthere were not twenty persons who knew the names I had mentioned to onewho knew Wieland's name. Then the class became generally disorderly. Myfeeling of embarrassment gained in depth. Finally, as a climax, severalquite young girls, about ten years and less, came and joined the class. The dream broke off abruptly as I was in the act of taking thesechildren to the wife of an old college tutor, to protest against theiradmission. It is worth noting, perhaps, that in this evolution of feeling indreaming the quality of the emotion may vary within certain limits. Oneshade of feeling may be followed by another and kindred shade, so thatthe whole dream still preserves a degree, though a less obvious degree, of emotional unity. Thus, for example, a lady friend of mine once dreamtthat she was in church, listening to a well-known novelist of the moreearnest sort, preaching. A wounded soldier was brought in to be shot, because he was mortally wounded, and had distinguished himself by hisbravery. He was then shot, but not killed, and, rolling over in agony, exclaimed, "How long!" The development of an extreme emotion of horrorout of the vague feeling of awe which is associated with a church, givesa curious interest to this dream. _Verisimilitude in Dreams. _ I must not dwell longer on this emotional basis of dreams, but pass tothe consideration of the second and objective kind of unity whichcharacterizes many of our more elaborate dream-performances. In spite ofall that is fitful and grotesque in dream-combination, it stillpreserves a distant resemblance to our actual experience. Though nodream reproduces a particular incident or chain of incidents in thisexperience, though the dream-fancy invariably transforms the particularobjects, relations, and events of waking life, it still makes the orderof our daily experience its prototype. It fashions its imaginary worldon the model of the real. Thus, objects group themselves in space, andact on one another conformably to these perceived space-relations;events succeed one another in time, and are often seen to be connected;men act from more or less intelligible motives, and so on. In this way, though the dream-fancy sets at nought the particular relations of ourexperience, it respects the general and constant relations. How are weto account for this? It is said by certain philosophers that this superposition of therelations of space, time, causation, etc. , on the products of ourdream-fancy is due to the fact that all experience arises by a synthesisof mental forms with the chaotic matter of sense-impressions. Thesephilosophers allow, however, that all particular connections aredetermined by experience. Accordingly, what we have to do here is toinquire how far this scientific method of explaining mental connectionsby facts of experience will carry us. In other words, we have to askwhat light can be thrown on these tendencies of dream-imagination byascertained psychological laws, and more particularly by what are knownas the laws of association. These laws tell us that of two mental phenomena which occur together, each will tend to recall the other whenever it happens to be revived. Onthe physiological side, this means that any two parts of the nervousstructures which have acted together become in some way connected, sothat when one part begins to work the other will tend to work also. Butit is highly probable that a particular structure acts in a great manydifferent ways. Thus, it may be stimulated by unlike modes of stimuli, or it may enter into very various connections with other structures. What will follow from this? One consequence would appear to be thatthere will be developed an organic connection between the twostructures, of such a kind that whenever one is excited the other willbe disposed to act somehow and anyhow, even when there is nothing in thepresent mode of activity of the first structure to determine the secondto act in some one definite way, in other words, when this mode ofactivity is, roughly speaking, novel. Let me illustrate this effect in one of the simplest cases, that of thevisual organ. If, when walking out on a dark night, a few points in myretina are suddenly stimulated by rays of light, and I recognize someluminous object in a corresponding direction, I am prepared to seesomething above and below, to the right and to the left of this object. Why is this? There may from the first have been a kind of innateunderstanding among contiguous optic fibres, predisposing them to suchconcerted action. But however this be, this disposition would seem tohave been largely promoted by the fact that, throughout my experience, the stimulation of any retinal point has been connected with that ofadjoining points, either simultaneously by some second object, orsuccessively by the same object as the eye moves over it, or as theobject itself moves across the field of vision. When, therefore, in sleep any part of the optic centres is excited in aparticular way, and the images thus arising have their correspondingloci in space assigned to them, there will be a disposition to refer anyother visual images which happen at the moment to arise in consciousnessto adjacent parts of space. The character of these other images will bedetermined by other special conditions of the moment; their locality orposition in space will be determined by this organic connection. We may, perhaps, call these tendencies to concerted action of some kind generalassociative dispositions. Just as there are such dispositions to united action among various partsof one organ of sense, so there may be among different organs, which areeither connected originally in the infant organism, or havecommunications opened up by frequent coexcitation of the two. Such linksthere certainly are between the organs of taste and smell, and betweenthe ear and the muscular system in general, and more particularly thevocal organ. [96] A new odour often sets us asking how the object wouldtaste, and a series of sounds commonly disposes us to movement of somekind or another. How far there may be finer threads of connectionbetween other organs, such as the eye and the ear, which do not betraythemselves amid the stronger forces of waking mental life, one cannotsay. Whatever their number, it is plain that they will exert theirinfluence within the comparatively narrow limits of dream-life, servingto impress a certain character on the images which happen to be calledup by special circumstances, and giving to the combination a slightmeasure of congruity. Thus, if I were dreaming that I heard some livelymusic, and at the same time an image of a friend was anyhow excited, mydream-fancy might not improbably represent this person as performing asequence of rhythmic movements, such as those of riding, dancing, etc. A narrower field for these general associative dispositions may be foundin the tendency, on the reception of an impression of a given character, to look for a certain kind of second impression; though the exact natureof this is unknown. Thus, for example, the form and colour of a newflower suggest a scent, and the perception of a human form isaccompanied by a vague representation of vocal utterances. These generaltendencies of association appear to me to be most potent influences inour dream-life. The many strange human forms which float before ourdream-fancy are apt to talk, move, and behave like men and women ingeneral, however little they resemble their actual prototypes, andhowever little individual consistency of character is preserved by eachof them. Special conditions determine what they shall say or do; thegeneral associative disposition accounts for their saying or doingsomething. We thus seem to find in the purely passive processes of association someground for that degree of natural coherence and rational order which ourmore mature dreams commonly possess. These processes go far to explain, too, that odd mixture of rationality with improbability, of naturalorder and incongruity, which characterizes our dream-combinations. _Rational Construction in Dreams. _ Nevertheless, I quite agree with Herr Volkelt that association, even inthe most extended meaning, cannot explain all in the shaping of ourdream-pictures. The "phantastical power" which Cudworth talks aboutclearly includes something besides. It is an erroneous supposition thatwhen we are dreaming there is a complete suspension of the voluntarypowers, and consequently an absence of all direction of the intellectualprocesses. This supposition, which has been maintained by numerouswriters, from Dugald Stewart downwards, seems to be based on the factthat we frequently find ourselves in dreams striving in vain to move thewhole body or a limb. But this only shows, as M. Maury remarks in thework already referred to, that our volitions are frustrated through theinertia of our bodily organs, not that these volitions do not takeplace. In point of fact, the dreamer, not to speak of the somnambulist, is often conscious of voluntarily going through a series of actions. This exercise of volition is shown unmistakably in the well-knowninstances of extraordinary intellectual achievements in dreams, asCondillac's composition of a part of his _Cours d'Études_. No one wouldmaintain that a result of this kind was possible in the total absence ofintellectual action carefully directed by the will. And something ofthis same control shows itself in all our more fully developed dreams. One manifestation of this voluntary activity in sleep is to be found inthose efforts of attention which not unfrequently occur. I have remarkedthat, speaking roughly and in relation to the waking condition, thestate of sleep is marked by a subjection of the powers of attention tothe force of the mental images present to consciousness. Yet somethingresembling an exercise of voluntary attention sometimes happens insleep. The intellectual feats just spoken of, unless, indeed, they arereferred to some mysterious unconscious mental operations, clearlyinvolve a measure of volitional guidance. All who dream frequently areoccasionally aware on awaking of having greatly exercised theirattention on the images presented to them during sleep. I myself amoften able to recall an effort to see beautiful objects, whichthreatened to disappear from my field of vision, or to catch faintreceding tones of preternatural sweetness; and some dreamers allege thatthey are able to retain a recollection of the feeling of strainconnected with such exercise of attention in sleep. The main function of this voluntary attention in dream-life is seen inthe selection of those images which are to pass the threshold of clearconsciousness. I have already spoken of a selective action brought aboutby the ruling emotion. In this case, the attention is held captive bythe particular feeling of the moment. Also a selective process goes onin the case of the action of those associative dispositions justreferred to. But in each of these cases the action of selectiveattention is comparatively involuntary, passive, and even unconscious, not having anything of the character of a conscious striving to compasssome end. Besides this comparatively passive play of selectiveattention, there is an active play, in which there is a conscious wishto gain an end; in other words, the operation of a definite motive. Thismotive may be described as an intellectual impulse to connect andharmonize what is present to the mind. The voluntary kind of selectionincludes and transcends each of the involuntary kinds. It has as itsresult an imitation of that order which is brought about by what I havecalled the associative dispositions, only it consciously aims at thisresult. And it is a process controlled by a feeling, namely, theintellectual sentiment of consistency, which is not a mode of emotionalexcitement enthralling the will, but a calm motive, guiding theactivities of attention. It thus bears somewhat the same relation to theemotional selection already spoken of, as dramatic creation bears tolyrical composition. This process of striving to seize some connecting link, or thread oforder, is illustrated whenever, in waking life, we are suddenly broughtface to face with an unfamiliar scene. When taken into a factory, westrive to arrange the bewildering chaos of visual impressions under somescheme, by help of which we are said to understand the scene. So, if onentering a room we are plunged in _medias res_ of a lively conversation, we strive to find a clue to the discussion. Whenever the meaning of ascene is not at once clear, and especially whenever there is anappearance of confusion in it, we are conscious of a painful feeling ofperplexity, which acts as a strong motive to ever-renewed attention. [97] In touching on this intellectual impulse to connect the disconnected, weare, it is plain, approaching the question of the very foundations ofour intellectual structure. That there is this impulse firmly rooted inthe mature mind nobody can doubt; and that it manifests itself in earlylife in the child's recurring "Why?" is equally clear. But how we are toaccount for it, whether it is to be viewed as a mere result of the playof associated fragments of experience, or as something involved in thevery process of the association of ideas itself, is a question intowhich I cannot here enter. What I am here concerned to show is that the search for consistency andconnection in the manifold impressions of the moment is a deeply rootedhabit of the mind, and one which is retained in a measure during sleep. When, in this state, our minds are invaded by a motley crowd ofunrelated images, there results a disagreeable sense of confusion; andthis feeling acts as a motive to the attention to sift out thoseproducts of the dream-fancy which may be made to cohere. When once thefoundations of a dream-action are laid, new images must to some extentfit in with this; and here there is room for the exercise of a distinctimpulse to order the chaotic elements of dream-fancy in certain forms. The perception of any possible relation between one of the crowd of newimages ever surging above the level of obscure consciousness, and theold group at once serves to detain it. The concentration of attention onit, in obedience to this impulse to seek for an intelligible order, atonce intensifies it and fixes it, incorporating it into the series ofdream-pictures. Here is a dream which appears to illustrate this impulse to seek anintelligible order in the confused and disorderly. After being occupiedwith correcting the proofs of my volume on _Pessimism_, I dreamt that mybook was handed to me by my publisher, fully illustrated with colouredpictures. The frontispiece represented the fantastic figure of a mangesticulating in front of a ship, from which he appeared to have juststepped. My publisher told me it was meant for Hamlet, and I immediatelyreflected that this character had been selected as a concrete example ofthe pessimistic tendency. I may add that, on awaking, I was distinctlyaware of having felt puzzled when dreaming, and of having striven toread a meaning into the dream. The _rationale_ of this dream seems to me to be somewhat as follows. Theimage of the completed volume represented, of course, a recurringanticipatory image of waking life. The coloured plates were due probablyto subjective optical sensations simultaneously excited, which were madeto fit in (with or without an effort of voluntary attention) with theimage of the book under the form of illustrations. But this stage ofcoherency did not satisfy the mind, which, still partly confused by theincongruity of coloured plates in a philosophic work, looked for acloser connection. The image of Hamlet was naturally suggested inconnection with pessimism. The effort to discover a meaning in thepictures led to the fusion of this image with one of the subjectivespectra, and in this way the idea of a Hamlet frontispiece probablyarose. The whole process of dream-construction is clearly illustrated in acurious dream recorded by Professor Wundt. [98] Before the house is afuneral procession: it is the burial of a friend, who has in realitybeen dead for some time past. The wife of the deceased bids him and anacquaintance who happens to be with him go to the other side of thestreet and join the procession. After she has gone away, his companionremarks to him, "She only said that because the cholera rages overyonder, and she wants to keep this side of the street to herself. " Thencomes an attempt to flee from the region of the cholera. Returning tohis house, he finds the procession gone, but the street strewn withrich nosegays; and he further observes crowds of men who seem to befuneral attendants, and who, like himself, are hastening to join theprocession. These are, oddly enough, dressed in red. When hurrying on, it occurs to him that he has forgotten to take a wreath for the coffin. Then he wakes up with beating of the heart. The sources of this dream are, according to Wundt, as follows. First ofall, he had, on the previous day, met the funeral procession of anacquaintance. Again, he had read of cholera breaking out in a certaintown. Once more, he had talked about the particular lady with thisfriend, who had narrated facts which clearly proved her selfishness. Thehastening to flee from the infected neighbourhood and to overtake theprocession was prompted by the sensation of heart-beating. Finally, thecrowd of red bier-followers, and the profusion of nosegays, owed theirorigin to subjective visual sensations, the "light-chaos" which oftenappears in the dark. Let us now see for a moment how these various elements may have becomefused into a connected chain of events. First of all, it is clear thatthis dream is built up on a foundation of a gloomy tone of feeling, arising, as it would seem, from an irregularity of the heart's action. Secondly, it owes its special structure and its air of a connectedsequence of events, to those tendencies, passive and active, to orderthe chaotic of which I have been speaking. Let us try to trace this outin detail. To begin with, we may suppose that the image of the procession occupiesthe dreamer's mind. From quite another source the image of the ladyenters consciousness, bringing with it that of her deceased husband andof the friend who has recently been talking about her. These newelements adapt themselves to the scene, partly by the passive mechanismof associative dispositions, and partly, perhaps, by the activity ofvoluntary selection. Thus, the idea of the lady's husband wouldnaturally recall the fact of his death, and this would fall in with thepre-existing scene under the form of the idea that he is the person whois now being buried. The next step is very interesting. The image of thelady is associated with the idea of selfish motives. This would tend tosuggest a variety of actions, but the one which becomes a factor of thedream is that which is specially adapted to the pre-existingrepresentations, namely, of the procession on the further side of thestreet, and the cholera (which last, like the image of the funeral, is, we may suppose, due to an independent central excitation). That is tosay, the request of the lady, and its interpretation, are a _resultant_of a number of adaptative or assimilative actions, under the sway of astrong desire to connect the disconnected, and a lively activity ofattention. Once more, the feeling of oppression of the heart, and thesubjective stimulation of the optic nerve, might suggest numberlessimages besides those of anxious flight and of red-clad men and nosegays;they suggest these, and not others, in this particular case, because ofthe co-operation of the impulse of consistency, which, setting out withthe pre-existing mental images, selects from among many tendencies ofreproduction those which happen to chime in with the scene. _The Nature of Dream-Intelligence. _ It must not be supposed that this process of welding together thechaotic materials of our dreams is ever carried out with anything likethe clear rational purpose of which we are conscious when seeking, inwaking life, to comprehend some bewildering spectacle. At best it is avague longing, and this longing, it may be added, is soon satisfied. There is, indeed, something, almost pathetic in the facility with whichthe dreamer's mind can be pacified with the least appearance of aconnection. Just as a child's importunate "Why?" is often silenced by aridiculous caricature of an explanation, so the dreamer's intelligenceis freed from its distress by the least semblance of a uniting order. It thus remains true with respect even to our most coherent dreams, thatthere is a complete suspension, or at least a considerable retardation, of the highest operations of judgment and thought; also a greatenfeeblement, to say the least of it, of those sentiments such as thefeeling of consistency and the sense of the absurd which are sointimately connected with these higher intellectual operations. In order to illustrate how oddly our seemingly rational dreamscaricature the operations of waking thought, I may, perhaps, be allowedto record two of my own dreams, of which I took careful note at thetime. On the first occasion I went "in my dream" to the "Stores" in August, and found the place empty. A shopman brought me some large fowls. Iasked their price, and he answered, "Tenpence a pound. " I then askedtheir weight, so as to get an idea of their total cost, and he replied, "Forty pounds. " Not in the least surprised, I proceeded to calculatetheir cost: 40x10=400÷12=33-1/3. But, oddly enough, I took this quotientas pence, just as though I had not already divided by 12, and so madethe cost of a fowl to be 2s. 9d. , which seemed to me a fair enoughprice. In my second dream I was at Cambridge, among a lot of undergraduates. Isaw a coach drive up with six horses. Three undergraduates got out ofthe coach. I asked them why they had so many horses, and they said, "Because of the luggage. " I then said, "The luggage is much more thanthe undergraduates. Can you tell me how to express this in mathematicalsymbols? This is the way: if _x_ is the weight of an undergraduate, then_x_ + _x_. N represents the weight of an undergraduate and his luggagetogether. " I noticed that this sally was received with evidentenjoyment. [99] We may say, then, that the structure of our dreams, equally with thefact of their completely illusory character, points to the conclusionthat during sleep, just as in the moments of illusion in waking life, there is a deterioration of our intellectual life. The highestintellectual activities answering to the least stable nervousconnections are impeded, and what of intellect remains corresponds tothe most deeply organized connections. In this way, our dream-life touches that childish condition of theintelligence which marks the decadence of old age and the encroachmentsof mental disease. The parallelism between dreams and insanity has beenpointed out by most writers on the subject. Kant observed that themadman is a dreamer awake, and more recently Wundt has remarked that, when asleep, we "can experience nearly all the phenomena which meet usin lunatic asylums. " The grotesqueness of the combinations, the lack ofall judgment as to consistency, fitness, and probability, are commoncharacteristics of the short night-dream of the healthy and the longday-dream of the insane. [100] But one great difference marks off the two domains. When dreaming, weare still sane, and shall soon prove our sanity. After all, the dream ofthe sleeper is corrected, if not so rapidly as the illusion of thehealthy waker. As soon as the familiar stimuli of light and sound setthe peripheral sense-organs in activity, and call back the nervoussystem to its complete round of healthy action, the illusion disappears, and we smile at our alarms and agonies, saying, "Behold, it was adream!" On the practical side, the illusions and hallucinations of sleep must beregarded as comparatively harmless. The sleeper, in healthy conditionsof sleep, ceases to be an agent, and the illusions which enthral hisbrain have no evil practical consequences. They may, no doubt, as weshall see in a future chapter, occasionally lead to a subsequentconfusion of fiction and reality in waking recollection. But with theexception of this, their worst effect is probably the lingering sense ofdiscomfort which a "nasty dream" sometimes leaves with us, though thismay be balanced by the reverberations of happy dream-emotions whichsometimes follow us through the day. And however this be, it is plainthat any disadvantages thus arising are more than made good by theconsideration that our liability to these nocturnal illusions isconnected with the need of that periodic recuperation of the highernervous structures which is a prime condition of a vigorous intellectualactivity, and so of a triumph over illusion during waking life. For these reasons dreams may properly be classed with the illusions ofnormal or healthy life, rather than with those of disease. Theycertainly lie nearer this region than the very similar illusions of thesomnambulist, which with respect to their origin appear to be moredistinctly connected with a pathological condition of the nervoussystem, and which, with respect to their practical consequences mayeasily prove so disastrous. _After-Dreams. _ In concluding this account of dreams, I would call attention to theimportance of the transition states between sleeping and waking, inrelation to the production of sense-illusion. And this point may betouched on here all the more appropriately, since it helps to bring outthe close relation between waking and sleeping illusion. The mind doesnot pass suddenly and at a bound from the condition of dream-fancy tothat of waking perception. I have already had occasion to touch on the"hypnagogic state, " that condition of somnolence or "sleepiness" inwhich external impressions cease to act, the internal attention isrelaxed, and the weird imagery of sleep begins to unfold itself. Andjust as there is this anticipation of dream-hallucination in thepresomnial condition, so there is the survival of it in the postsomnialcondition. As I have observed, dreams sometimes leave behind them, foran appreciable interval after waking, a vivid after-impression, and insome cases even the semblance of a sense-perception. If one reflects how many ghosts and other miraculous apparitions areseen at night, and when the mind is in a more or less somnolentcondition, the idea is forcibly suggested that a good proportion ofthese visions are the _débris_ of dreams. In some cases, indeed, as thatof Spinoza, already referred to, the hallucination (in Spinoza's casethat of "a scurvy black Brazilian") is recognized by the subject himselfas a dream-image. [101] I am indebted to Mr. W. H. Pollock for a factwhich curiously illustrates the position here adopted. A lady wasstaying at a country house. During the night and immediately on wakingup she had an apparition of a strange-looking man in mediæval costume, a figure by no means agreeable, and which seemed altogether unfamiliarto her. The next morning, on rising, she recognized the original of herhallucinatory image in a portrait hanging on the wall of her bedroom, which must have impressed itself on her brain before the occurrence ofthe apparition, though she had not attended to it. Oddly enough, she nowlearnt for the first time that the house at which she was staying hadthe reputation of being haunted, and by the very same somewhatrepulsive-looking mediæval personage that had troubled herinter-somnolent moments. The case seems to me to be typical with respectto the genesis of ghosts, and of the reputation of haunted houses. * * * * * NOTE. THE HYPNOTIC CONDITION. I have not in this chapter discussed the relation of dreaming tohypnotism, or the state of artificially produced quasi-sleep, becausethe nature of this last is still but very imperfectly understood. Inthis condition, which is induced in a number of ways by keeping theattention fixed on some non-exciting object, and by weak continuous andmonotonous stimulation, as stroking the skin, the patient can be made toact conformably to the verbal or other suggestion of the operator, or tothe bodily position which he is made to assume. Thus, for example, if aglass containing ink is given to him, with the command to drink, heproceeds to drink. If his hands are folded, he proceeds to act as if hewere in church, and so on. Braid, the writer who did so much to get at the facts of hypnotism, andDr. Carpenter who has helped to make known Braid's careful researches, regard the actions of the hypnotized subject as analogous to ideomotormovements; that is to say, the movements due to the tendency of an ideato act itself out apart from volition. On the other hand, one of thelatest inquirers into the subject, Professor Heidenhain, of Breslau, appears to regard these actions as the outcome of "unconsciousperceptions" (_Animal Magnetism_, English translation, p. 43, etc. ). In the absence of certain knowledge, it seems allowable to argue fromthe analogy of natural sleep that the actions of the hypnotized patientare accompanied with the lower forms of consciousness, includingsensation and perception, and that they involve dream-likehallucinations respecting the external circumstances of the moment. Regarding them in this light, the points of resemblance betweenhypnotism and dreaming are numerous and striking. Thus, Dr. Heidenhaintells us that the threshold or liminal value of stimulation is loweredjust as in ordinary sleep sense-activity as a whole is lowered. According to Professor Weinhold, the hypnotic condition begins in agradual loss of taste, touch, and the sense of temperature; then sightis gradually impaired, while hearing remains throughout the leastinterfered with. [102] In this way, the mind of the patient is largelycut off from the external world, as in sleep, and the power oforientation is lost. Moreover, there are all the conditions present, both positive and negative, for the hallucinatory transformation ofmental images into percepts just as in natural sleep. Thus, the highercentres connected with the operations of reflection and reasoning arethrown _hors de combat_ or, as Dr. Heidenhain has it, "inhibited. " The condition of hypnotism is marked off from that of natural sleep, first of all, by the fact that the accompanying hallucinations arewholly due to external suggestion (including the effects of bodilyposture). Dreams may, as we have seen, be very faintly modified byexternal influences, but during sleep there is nothing answering to theperfect control which the operator exercises over the hypnotizedsubject. The largest quantity of our "dream-stuff" comes, as we haveseen, from within and not from without the organism. And this factaccounts for the chief characteristic difference between the natural andthe hypnotic dream. The former is complex, consisting of crowds ofimages, and continually changing: the latter is simple, limited, andpersistent. As Braid remarks, the peculiarity of hypnotism is that theattention is concentrated on a remarkably narrow field of mental imagesand ideas. So long as a particular bodily posture is assumed, so longdoes the corresponding illusion endure. One result of this, inconnection with that impairing of sensibility already referred to, isthe scope for a curious overriding of sense-impressions by the dominantillusory percept, a process that we have seen illustrated in the activesense-illusions of waking life. Thus, if salt water is tasted and thepatient is _told_ that it is beer, he complains that it is sour. In being thus in a certain rapport, though so limited and unintelligenta rapport, with the external world, the mind of the hypnotized patientwould appear to be nearer the condition of waking illusion than is themind of the dreamer. It must be remembered, however, and this is thesecond point of difference between dreaming and hypnotism, that thehypnotized subject tends _to act out_ his hallucinations. Hisquasi-percepts are wont to transform themselves into actions with adegree of force of which we see no traces in ordinary sleep. Why thereshould be this greater activity of the motor organs in the one conditionthan in the other, seems to be a point as yet unexplained. Allsense-impressions and percepts are doubtless accompanied by some degreeof impulse to movement, though, for some reason or another, in naturaland healthy sleep these impulses are restricted to the stage of faintnascent stirrings of motor activity which hardly betray themselvesexternally. This difference, involving a great difference in thepossible practical consequences of the two conditions of natural andhypnotic sleep, clearly serves to bring the latter condition nearer tothat of insanity than the former condition is brought. A strongsusceptibility to the hypnotic influence, such as Dr. Heidenhaindescribes, might, indeed, easily prove a very serious want of"adaptation of internal to external relations, " whereas a tendency todreaming would hardly prove a maladaptation at all. CHAPTER VIII. ILLUSIONS OF INTROSPECTION. We have now, perhaps, sufficiently reviewed sense-illusions, both ofwaking life and of sleep. And having roughly classified them accordingto their structure and origin, we are ready to go forwards and inquirewhether the theory thus reached can be applied to other forms ofillusory error. And here we are compelled to inquire at the outset ifanything analogous to sense-illusion is to be found in that other greatregion of presentative cognition usually marked off from externalperception as internal perception, self-reflection, or introspection. _Illusions of Introspection defined. _ This inquiry naturally sets out with the question: What is meant byintrospection? This cannot be better defined, perhaps, than by sayingthat it is the mind's immediate reflective cognition of its own statesas such. In one sense, of course, everything we know may be called a mentalstate, actual or imagined. Thus, a sense-impression is known, exactlylike any other feeling of the mind, as a mental phenomenon or mentalmodification. Yet we do not usually speak of introspectivelyrecognizing a sensation. Our sense-impressions are marked off from allother feelings by having an objective character, that is to say, animmediate relation to the external world, so that in attending to one ofthem our minds pass away from themselves in what Professor Bain callsthe attitude of objective regard. Introspection is confined to feelingswhich want this intimate connection with the external region, andincludes sensation only so far as it is viewed apart from externalobjects and on its mental side as a feeling, a process which is next toimpossible where the sensation has little emotional colour, as in thecase of an ordinary sensation of sight or of articulate sound. This being so, errors of introspection, supposing such to be found, willin the main be sufficiently distinguished from those of perception. Evenan hallucination of sense, whether setting out from a subjectivesensation or not, always contains the semblance of a sense-impression, and so would not be correctly classed with errors of introspection. Just as introspection must be marked off from perception, so must it bedistinguished from memory. It may be contended that, strictly speaking, all introspection is retrospection, since even in attending to a presentfeeling the mind is reflectively representing to itself the immediatelypreceding momentary experience of that feeling. Yet the adoption of thisview does not hinder us from drawing a broad distinction between acts ofintrospection and acts of memory. Introspection must be regarded asconfined to the knowledge of immediately antecedent mental states withreference to which, no error of memory can be supposed to arise. It follows from this that an illusion of introspection could only befound in connection with the apprehension of present or immediatelyantecedent mental states. On the other hand, any illusions connectedwith the consciousness of personal continuity and identity would fallrather under the class of mnemonic than that of introspective error. Once more, introspection must be carefully distinguished from what Ihave called belief. Some of our beliefs may be found to grow out of andbe compounded of a number of introspections. Thus, my conception of myown character, or my psychological conception of mind as a whole, may beseen to arise by a combination of the results of a number of acts ofintrospection. Yet, supposing this to be so, we must still distinguishbetween the single presentative act of introspection and therepresentative belief growing out of it. It follows from this that, though an error of the latter sort mightconceivably have its origin in one of the former; though, for example, aman's illusory opinion of himself might be found to involve errors ofintrospection, yet the two kinds of illusion would be sufficientlyunlike. The latter would be a simple presentative error, the former acompound representative error. Finally, in order to complete this preliminary demarcation of oursubject-matter, it is necessary to distinguish between an introspection(apparent or real) of a feeling or idea, and a process of inferencebased on this feeling. The term introspective knowledge must, it isplain, be confined to what is or appears to be in the mind at the momentof inspection. By observing this distinction, we are in a position to mark off an_illusion_ of introspection from a _fallacy_ of introspection. Theformer differs from the latter in the absence of anything like aconscious process of inference. Thus, if we suppose that the derivationby Descartes of the fact of the existence of God from his possession ofthe idea to be erroneous, such a consciously performed act of reasoningwould constitute a fallacy rather than an illusion of introspection. We may, then, roughly define an illusion of introspection as an errorinvolved in the apprehension of the contents of the mind at any moment. If we mistake the quality or degree of a feeling or the structure of acomplex mass of feeling, or if we confuse what is actually present tothe mind with some inference based on this, we may be said to fall intoan illusion of introspection. But here the question will certainly be raised: How can we conceive themind erring as to the nature of its present contents; and what is todetermine, if not my immediate act of introspection, what is present inmy mind at any moment? Indeed, to raise the possibility of error inintrospection seems to do away with the certainty of presentativeknowledge. If, however, the reader will recall what was said in an earlier chapterabout the possibility of error in recognizing the quality of asense-impression, he will be prepared for a similar possibility here. What we are accustomed to call a purely presentative cognition is, intruth, partly representative. A feeling as pure feeling is not known; itis only known when it is distinguished, as to quality or degree, and soclassed or brought under some representation of a kind or description offeeling, as acute, painful, and so on. The accurate recognition of animpression of colour depends, as we have seen, on this process ofclassing being correctly performed. Similarly, the recognition ofinternal feelings implies the presence of the appropriate orcorresponding class-representation. Accordingly, if it is possible for awrong representation to get substituted for the right one, there seemsto be an opening for error. Any error that would thus arise can, of course, only be determined assuch in relation to some other act of introspection of the same mind. Inmatters of internal perception other minds cannot directly assist us incorrecting error as they can in the case of external perception, though, as we shall see by-and-by, they may do so indirectly. The standard ofreality directly applicable to introspective cognition is plainly whatthe individual mind recognizes at its best moments, when the processesof attention and classifying are accurately performed, and therepresentation may be regarded with certainty as answering to thefeeling. In other words, in the sphere of internal, as in that ofexternal experience, the criterion of reality is the average andperfect, as distinguished from the particular variable and imperfect actof cognition. We see, then, that error in the process of introspection is at leastconceivable. And now let us examine this process a little further, inorder to find out what probabilities of error attach to it. To begin with, then, an act of introspection, to be complete, clearlyinvolves the apprehension of an internal feeling or idea as somethingmental and marked off from the region of external experience. Thisdistinct recognition of internal states of mind as such, in oppositionto external impressions, is by no means easy, but presupposes a certaindegree of intellectual culture, and a measure of the power of abstractattention. _Confusion of Internal and External Experience. _ Accordingly, we find that where this is wanting there is a manifestdisposition to translate internal feelings into terms of externalimpressions. In this way there may arise a slight amount of habitual andapproximately constant error. Not that the process approaches to one ofhallucination; but only that the internal feelings are intuited ashaving a cause or origin analogous to that of sense-impressions. Thus tothe uncultivated mind a sudden thought seems like an audibleannouncement from without. The superstitious man talks of being led bysome good or evil spirit when new ideas arise in his mind or newresolutions shape themselves. To the simple intelligence of the boorevery thought presents itself as an analogue of an audible voice, and hecommonly describes his rough musings as saying this and that to himself. And this, mode of viewing the matter is reflected even, in the languageof cultivated persons. Thus we say, "The idea struck me, " or "was bornein on me, " "I was forced to do so and so, " and so on, and in thismanner we tend to assimilate internal to external mental phenomena. Much the same thing shows itself in our customary modes of describingour internal feelings of pleasure and pain. When a man in a state ofmental depression speaks of having "a load" on his mind it is evidentthat he is interpreting a mental by help of an analogy to a bodilyfeeling. Similarly, when we talk of the mind being torn by doubt or wornby anxiety. It would seem as though we tended mechanically to translatemental pleasures and pains into the language of bodily sensations. The explanation of this deeply rooted tendency to a slightly illusoryview of our mental states is, I think, an easy one. For one thing, itfollows from the relation of the mental image to the sense-impressionthat we should tend to assimilate the former to the latter as to itsnature and origin. This would account for the common habit of regardingthoughts, which are of course accompanied by representatives of theirverbal symbols, as internal voices, a habit which is probably especiallycharacteristic of the child and the uncivilized man, as we have found itto be characteristic of the insane. Another reason, however, must be sought for the habit of assimilatinginternal feelings to external sensations. If language has been evolvedas an incident of social life, at once one of its effects and itscauses, it would seem to follow that it must have first shaped Itself tothe needs of expressing these common objective experiences which wereceive by way of our senses. Our habitual modes of thought, limited asthey are by language, retain traces of this origin. We cannot conceiveany mental process except by some vague analogy to a physical process. In other words, we can even now only think with perfect clearness whenwe are concerned with some object of common cognition. Thus, the sphereof external sensation and of physical agencies furnishes us with the onetype of thinkable thing or object of thought, and we habitually viewsubjective mental states as analogues of these. Still, it may be said that these slight nascent errors are hardly worthnaming, and the question would still appear to recur whether there areother fully developed errors deserving to rank along with illusions ofsense. Do we, it may be asked, ever actually mistake the quality, degree, or structure of our internal feelings in the manner hintedabove, and if so, what is the range of such error? In order toappreciate the risks of such error, let us compare the process ofself-observation with that of external perception with respect to thedifficulties in the way of accurate presentative knowledge. _Misreading of Internal Feelings. _ First of all, it is noteworthy that a state of consciousness at any onemoment is an exceedingly complex thing. It is made up of a mass offeelings and active impulses which often combine and blend in a mostinextricable way. External sensations come in groups, too, but as a rulethey do not fuse in apparently simple wholes as our internal feelingsoften do. The very possibility of perception depends on a cleardiscrimination of sense-elements, for example, the several sensationsof colour obtained by the stimulation of different parts of theretina. [103] But no such clearly defined mosaic of feelings presentsitself in the internal region: one element overlaps and partly losesitself in another, and subjective analysis is often an exceedinglydifficult matter. Our consciousness is thus a closely woven texture inwhich the mental eye often fails to trace the several threads orstrands. Moreover, there is the fact that many of these ingredients areexceedingly shadowy, belonging to that obscure region ofsub-consciousness which it is so hard to penetrate with the light ofdiscriminative attention. This remark applies with particular force tothat mass of organic feelings which constitutes what is known ascoenæsthesis; or vital sense. While, to speak figuratively, the minute anatomy of consciousness isthus difficult with respect to longitudinal sections of the mentalcolumn, it is no less difficult with respect to transverse sections. Under ordinary circumstances, external impressions persist so that theycan be transfixed by a deliberate act of attention, and objects rarelyflit over the external scene so rapidly as to allow us no time for acareful recognition of the impression. Not so in the case of theinternal region of mind. The composite states of consciousness justdescribed never remain perfectly uniform for the shortest conceivableduration. They change continually, just as the contents of thekaleidoscope vary with every shake of the instrument. Thus, one shadeof feeling runs into another in such a way that it is often impossibleto detect its exact quality; and even when the character of the feelingdoes not change, its intensity is undergoing alterations so that anaccurate observation of its quantity is impracticable. Also, in thisunstable shifting internal scene features may appear for a duration tooshort to allow of close recognition. In this way it happens that wecannot sharply divide the feeling of the moment from its antecedents andits consequents. If, now, we take these facts in connection with what has been said aboverespecting the nature of the process of introspection, the probabilityof error will be made sufficiently clear. To transfix any particularfeeling of the moment, to selectively attend to it, and to bring itunder the proper representation, is an operation that requires time, atime which, though short, is longer than the fugitive character of somuch of our internal mental life allows. From all of which it wouldappear to follow that it must be very easy to overlook, confuse, andtransform, both as to quality and as to quantity, the actual ingredientsof our internal consciousness. From these sources there spring a number of small errors ofintrospection which, to distinguish them from others to be spoken ofpresently, may be called passive. These would include all errors indetecting what is in consciousness due to the intricacies of thephenomena, and not aided by any strong basis. For example, a mentalstate may fail to disclose its component parts to introspectiveattention. Thus, a motive may enter into our action which is soentangled with other feelings as to escape our notice. The fainter thefeeling the greater the difficulty of detaching it and inspecting it inisolation. Again, an error of introspection may have its ground in thefugitive character of a feeling. If, for example, a man is asked whethera rapid action was a voluntary one, he may in retrospection easilyimagine that it was not so, when as a matter of fact the action waspreceded by a momentary volition. When a person exclaims, "I did a thinginadvertently or mechanically, " it often means that he did not note themotive underlying the action. Such transitory feelings which cannot atthe moment be seized by an act of attention are pretty certain todisappear at once, leaving not even a temporary trace in consciousness. We will now pass to the consideration of other illusions ofintrospection more analogous to what I have called the active illusionsof perception. In our examination of these we found that a purerepresentation may under certain circumstances simulate the appearanceof a presentation, that a mental image may approximate to asense-impression. In the case of the internal feelings this liabilityshows itself in a still more striking form. The higher feelings or emotions are distinguished from the simplesense-feelings in being largely representative. Thus, a feeling ofcontentment at any moment, though no doubt conditioned by the bodilystate and the character of the organic sensations or coenæsthesis, commonly depends for the most part on intellectual representations ofexternal circumstances or relations, and may be called an idealforetaste of actual satisfactions, such as the pleasures of success, ofcompanionship, and so on. This being so, it is easy for imagination tocall up a semblance of these higher feelings. Since they depend largelyon representation, a mere act of representation may suffice to excite adegree of the feeling hardly distinguishable from the actual one. Thus, to imagine myself as contented is really to see myself at the moment asactually contented. Again, the actor, though, as we shall see by-and-by, he does not feel all that the spectator is apt to attribute to him, tends, when vividly representing to himself a particular shade offeeling, to regard himself as actually feeling in this way. Thus, it issaid of Garrick, that when acting Richard III. , he felt himself for themoment to be a villain. We should expect from all this that in the act of introspection the mindis apt, within certain limits, to find what it is prepared to find. Andsince there is in these acts often a distinct wish to detect someparticular feeling, we can see how easy it must be for a man throughbias and a wrong focussing of the attention to deceive himself up to acertain point with respect to the actual contents of his mind. Let us examine one of these active illusions a little more fully. Itwould at first sight seem to be a perfectly simple thing to determine atany given moment whether we are enjoying ourselves, whether ouremotional condition rises above the pleasure-threshold or point ofindifference and takes on a positive hue of the agreeable orpleasurable. Yet there is good reason for supposing that people notunfrequently deceive themselves on this matter. It is, perhaps, hardlyan exaggeration to say that most of us are capable of imagining that weare having enjoyment when we conform to the temporary fashion of socialamusement. It has been cynically observed that people go into societyless in order to be happy than to seem so, and one may add that in thissemblance of enjoyment they may, provided they are not _blasé_, deceivethemselves as well as others. The expectation of enjoyment, theknowledge that the occasion is intended to bring about this result, therecognition of the external signs of enjoyment in others--all this mayserve to blind a man in the earlier stages of social amusement to hisactual mental condition. If we look closely into this variety of illusion, we shall see that itis very similar in its structure and origin to that kind of erroneousperception which arises from inattention to the actual impression of themoment under the influence of a strong expectation of somethingdifferent. The representation of ourselves as entertained dislodges fromour internal field of vision our actual condition, relegating this tothe region of obscure consciousness. Could we for a moment get rid ofthis representation and look at the real feelings of the time, we shouldbecome aware of our error; and it is possible that the process ofbecoming _blasé_ involves a waking up to a good deal of illusion of thekind. Just as we can thus deceive ourselves within certain limits as to ouremotional condition, so we can mistake the real nature of ourintellectual condition. Thus, when an idea is particularly grateful toour minds, we may easily imagine that we believe it, when in point offact all the time there is a sub-conscious process of criticism goingon, which if we attended to it for a moment would amount to a distinctact of disbelief. Some persons appear to be capable of going onhabitually practising this petty deceit on themselves, that is to say, imagining they believe what in fact they are strongly inclined to doubt. Indeed, this remark applies to all the grateful illusions respectingourselves and others, which will have to be discussed by-and-by. Theimpulse to hold to the illusion in spite of critical reflection, involves the further introspective illusion of taking a state of doubtfor one of assurance. Thus, the weak, flattered man or woman manages tokeep up a sort of fictitious belief in the truth of the words which areso pleasant to the ear. It is plain that the external conditions of life impose on theindividual certain habits of feeling which often conflict with hispersonal propensities. As a member of society he has a powerful motiveto attribute certain feelings to himself, and this motive acts as a biasin disturbing his vision of what is actually in his mind. While thisholds good of lighter matters, as that of enjoyment just referred to, itapplies still more to graver matters. Thus, for example, a man mayeasily persuade himself that he feels a proper sentiment of indignationagainst a perpetrator of some mean or cruel act, when as a matter offact his feeling is much more one of compassion for the previously likedoffender. In this way we impose on ourselves, disguising our realsentiments by a thin veil of make-believe. So far I have spoken of an illusion of introspection as analogous tothe slight misapprehensions of sense-impression which were touched on inconnection with illusions of sense (Chapter III. ). It is to be observed, however, that the confusing of elements of consciousness, which is soprominent a factor in introspective illusion, involves a species oferror closely analogous to a complete illusion of perception, that is tosay, one which involves a misinterpretation of a sense-impression. This variety of illusion is illustrated in the case in which a presentfeeling or thought is confounded with some inference based on it. Forexample, a present thought may, through forgetfulness, be regarded as anew discovery. Its originality appears to be immediately made known inthe very freshness which characterizes it. Every author probably hasundergone the experience of finding that ideas which started up to hismind as fresh creations, were unconscious reminiscences of his own or ofsomebody else's ideas. In the case of present emotional states this liability to confuse thepresent and the past is far greater. Here there is something hardlydistinguishable from an active illusion of sense-perception. In thiscondition of mind a man often says that he has an "intuition" ofsomething supposed to be immediately given in the feeling itself. Forinstance, one whose mind is thrilled by the pulsation of a new joyexclaims, "This is the happiest moment of my life, " and the assuranceseems to be contained in the very intensity of the feeling itself. Ofcourse, cool reflection will tell him that what he affirms is merely abelief, the accuracy of which presupposes processes of recollection andjudgment, but to the man's mind at the moment the supremacy of thisparticular joy is immediately intuited. And so with the assurance thatthe present feeling, for example of love, is undying, that it is equalto the most severe trials, and so on. A man is said to _feel_ at themoment that it is so, though as the facts believed have reference toabsent circumstances and events, it is plain that the knowledge is by nomeans intuitive. At such times our minds are in a state of pure feeling: intellectualdiscrimination and comparison are no longer possible. In this way ouremotions in the moments of their greatest intensity carry away ourintellects with them, confusing the region of pure imagination with thatof truth and certainty, and even the narrow domain of the present withthe vast domain of the past and future. In this condition differences ofpresent and future may be said to disappear and the energy of theemotion to constitute an immediate assurance of its existenceabsolutely. [104] The great region for the illustration of these active illusions is thatof the moral and religious life. With respect to our real motives, ourdominant aspirations, and our highest emotional experiences, we aregreatly liable to deceive ourselves. The moralist and the theologianhave clearly recognized the possibilities of self-deception in mattersof feeling and impulse. To them it is no mystery that the human heartshould mistake the fictitious for the real, the momentary and evanescentfor the abiding. And they have recognized, too, the double bias in theseerrors, namely, the powerful disposition to exaggerate the intensity andpersistence of a present feeling on the one hand, and on the other handto take a mere wish to feel in a particular way for the actualpossession of the feeling. _Philosophic Illusions. _ The opinion of theologians respecting the nature of moral introspectionpresents a singular contrast to that entertained by some philosophers asto the nature of self-consciousness. It is supposed by many of thesethat in interrogating their internal consciousness they are lifted aboveall risk of error. The "deliverance of consciousness" is to themsomething bearing the seal of a supreme authority, and must not becalled in question. And so they make an appeal to individualconsciousness a final resort in all matters of philosophical dispute. Now, on the face of it, it does not seem probable that this operationshould have an immunity from all liability to error. For the mattersrespecting which we are directed to introspect ourselves, are the mostsubtle and complex things of our intellectual and emotional life. Andsome of these philosophers even go so far as to affirm that the plainman is quite equal to the niceties of this process. It has been brought as a charge against some of these same philosophersthat they have based certain of their doctrines on errors ofintrospection. This charge must, of course, be received with some sortof suspicion here, since it has been brought forward by avowed disciplesof an opposite philosophic school. Nevertheless, as there is from ourpresent disinterested and purely scientific point of view a presumptionthat philosophers like other men are fallible, and since it is certainthat philosophical introspection does not materially differ from otherkinds, it seems permissible just to glance at some of these allegedillusions in relation to other and more vulgar forms. Further referenceto them will be made at the end of our study. These so-called philosophical illusions will be found, like the vulgarones just spoken of, to illustrate the distinction drawn between passiveand active illusions. That is to say, the alleged misreading ofindividual consciousness would result now from a confusion of distinctelements, including wrong suggestion, due to the intricacies of thephenomena, now from a powerful predisposition to read something into thephenomena. A kind of illusion in which the passive element seems most conspicuouswould be the error into which the interrogator of the individualconsciousness is said to fall respecting simple unanalyzable states ofmind. On the face of it, it is not likely that a mere inward glance atthe tangle of conscious states should suffice to determine what is sucha perfectly simple mental phenomenon. Accordingly, when a writerdeclares that an act of introspection demonstrates the simpleunanalyzable character of such a feeling as the sentiment of beauty orthat of moral approval, the opponent of this view clearly has some showof argument for saying that this simplicity may be altogether illusoryand due to the absence of a perfect act of attention. Similarly, when itis said that the idea of space contains no representations of muscularsensation, the statement may clearly arise from the want of asufficiently careful kind of introspective analysis. [105] In most cases of these alleged philosophical errors, however, the activeand passive factors seem to combine. There are certain intricacies inthe mental phenomenon itself favouring the chances of error, and thereare independent predispositions leading the mind to look at thephenomenon in a wrong way. This seems to apply to the famous declarationof a certain school of thinkers that by an act of introspection we canintuit the fact of liberty, that is to say, a power of spontaneousdetermination of action superior to and regulative of the influence ofmotives. It may be plausibly contended that this idea arises partlyfrom a mixing up of facts of present consciousness with inferences fromthem, and partly from a natural predisposition of the mind to investitself with this supreme power of absolute origination. [106] In a similar way, it might be contended that other famous philosophicdicta are founded on a process of erroneous introspection of subjectivemental states. In some cases, indeed, it seems a plausible explanationto regard these illusions as mere survivals in attenuated shadowy formof grosser popular illusions. But this is not yet the time to enter onthese, which, moreover, hardly fall perhaps under our definition of anillusion of introspection. _Value of the Introspective Method. _ In drawing up this rough sketch of the illusions of introspection, Ihave had no practical object in view. I have tried to look at the factsas they are apart from any conclusions to be drawn from them. Thequestion how far the liability to error in any region of inquiryvitiates the whole process is a difficult one; and the question whetherthe illusions to which we are subject in introspection materially affectthe value of self-knowledge as a whole and consequently of theintrospective method in psychology, as many affirm, is too subtle a oneto be fully treated now. All that I shall attempt here is to show thatit does not do this any more than the risk of sense-illusion can be saidmaterially to affect the value of external observation. It is to be noted first of all that the errors of introspection are muchmore limited than those of sense-perception. They broadly answer to theslight errors connected with the discrimination and recognition of thesense-impression. There is nothing answering to a complete hallucinationin the sphere of the inner mental life. It follows, too, from what hasbeen said above, that the amount of active error in introspection isinsignificant, since the representation of a feeling or belief is sovery similar to the actual experience of it. In brief, the errors of introspection, though numerous, are all tooslight to render the process of introspection as a whole unsound anduntrustworthy. Though, as we have seen, it involves, strictly speaking, an ingredient of representation, this fact does not do away with thebroad distinction between presentative and representative cognition. Introspection is presentative in the sense that the reality constitutingthe object of cognition, the mind's present feeling, is as directlypresent to the knowing mind as anything can be conceived to be. It maybe added that the power of introspection is a comparatively newacquisition of the human race, and that, as it improves, the amount oferror connected with its operation may reasonably be expected to becomeinfinitesimal. It is often supposed by those who undervalue the introspective method inpsychology that there is a special difficulty in the detection of errorin introspection, owing to the fact that the object of inspection issomething individual and private, and not open to common scrutiny as theobject of external perception. Yet, while allowing a certain force tothis objection I would point out, first of all, that even insense-perception, what the individual mind is immediately certain of isits own sensations. The relatively perfect certainty which finallyattaches to the presentative side of sense-perception is precisely thatwhich finally attaches to the results of introspection. In the second place, it may be said that the contrast between the innerand the outer experience is much less than it seems. In many cases ouremotions are the direct result of a common external cause, and even whenthey are not thus attached to some present external circumstance, we areable, it is admitted, by the use of language, roughly to compare ourindividual feelings. And such comparison is continually bringing tolight the fact that there is a continuity in our mental structure, thatour highest thoughts and emotions lead us back to our commonsense-impressions, and that consequently, in spite of all individualdifferences of temperament and mental organization, our inner experienceis in all its larger features a common experience. I may add that this supposition of the common nature of our internalexperience, as a whole, not only underlies the science of psychology, but is implied in the very process of detecting and correcting errors ofintrospection. I do not mean that in matters of feeling "authority" isto override "private judgment. " Our last resort with respect to thingsof the mind is, as I have said, that of careful self-inspection. And theprogress of psychology and the correction of illusion proceed by meansof an ever-improving exercise of the introspective faculty. Yet suchindividual inspection can at least be _guided_ by the results of others'similar inspection, and should be so guided as soon as a generalconsensus in matters of internal experience is fairly made out. In pointof fact, the preceding discussion of illusions of introspection hasplainly rested on the sufficiently verified assumption that the calmestand most efficient kind of introspection, in bringing to light what ispermanent as compared with what is variable in the individual cognition, points in the direction of a common body of introspected fact. CHAPTER IX. OTHER QUASI-PRESENTATIVE ILLUSIONS: ERRORS OF INSIGHT. Besides the perception of external objects, and the inspection of ourinternal mental states, there are other forms of quasi-presentativecognition which need to be touched on here, inasmuch as they aresometimes erroneous and illusory. In the last chapter I alluded to the fact that emotion may arise as theimmediate accompaniment of a sense-impression. When this is the casethere is a disposition to read into the external object a qualityanswering to the emotion, just as there is a disposition to ascribe toobjects qualities of heat and cold answering to the sensations thuscalled. And such a reference of an emotional result to an externalexciting cause approximates in character to an immediate intuition. Thecognition of the quality is instantaneous, and quite free from anyadmixture of conscious inference. Accordingly, we have to inquire intothe illusory forms of such intuition, if such there be. _Æsthetic Intuition. _ Conspicuous among these quasi-presentative emotional cognitions isæsthetic intuition, that is to say, the perception of an object asbeautiful. It is not necessary here to raise the question whether thereis, strictly speaking, any quality in things answering to the sentimentof beauty in our minds: this is a philosophical and not a psychologicalquestion, and turns on the further question, what we mean by object. Allthat we need to assume here is that there are certain aspects ofexternal things, certain relations of form, together with a power ofexciting certain pleasurable ideas in the spectator's mind, which arecommonly recognized as the cause of the emotion of beauty, and indeedregarded as constituting the embodiments of the objective quality, beauty. Æsthetic intuition thus clearly implies the immediate assuranceof the existence of a common source of æsthetic delight, a source boundup with an object of common sense-perception. And so we may say that tocall a thing beautiful is more or less distinctly to recognize it as acause of a present emotion, and to attribute to it a power of raising akindred emotion in other minds. _Æsthetic Illusion. _ According to this view of the matter, an illusion of æsthetic intuitionwould arise whenever this power of affecting a number of mindspleasurably is wrongly attributed, by an act of "intuition, " to anobject of sense-perception, on the ground of a present personalfeeling. Now, this error is by no means unfrequent. Our delight in viewingexternal things, though agreeing up to a certain point, does not agreethroughout. It is a trite remark that there is a large individualfactor, a considerable "personal equation, " in matters of taste, as inother matters. Permanent differences of natural sensibility, ofexperience, of intellectual habits, and so on, make an objectæsthetically impressive and valuable to one man and not to another. Yetthese differences tend to be overlooked. The individual mind, filledwith delight at some spectacle, automatically projects its feelingoutwards in the shape of a cause of a common sentiment. And the force ofthis impulse cannot be altogether explained as the effect of pastexperiences and of association. It seems to involve, in addition, theplay of social instincts, the impulse of the individual mind to connectitself in sympathy with the collective mind. Here, as in the other varieties of illusion already treated of, we maydistinguish between a passive and an active side; only in this case thepassive side must not be taken as corresponding to any commonsuggestions of the object, as in the case of perception proper. So faras an illusion of æsthetic intuition may be considered as passive, itmust be due to the effect of circumscribed individual associations withthe object. All agree that what is called beauty consists, to a considerable extent, of a power of awaking pleasant suggestions, but in order that theseshould constitute a ground of æsthetic value, they must be common, participated in by all, or at least by an indefinite number. This willbe the case when the association rests on our common every-dayexperiences, and our common knowledge of things, as in the case of thepeaceful beauty of an ascending curl of blue smoke in a woody landscape, or the awful beauty of a lofty precipice. On the other hand, when theexperience and recollections, which are the source of the pleasure, arerestricted and accidental, any attribution of objective worth isillusory. Thus, the ascription of beauty to one's native village, toone's beloved friends, and so on, in so far as it carries the convictionof objective worth, may imply a confusion of the individual with thecommon experience. The active side of this species of illusions would be illustrated inevery instance of ascribing beauty to objects which is due, in aconsiderable measure at least, to some pre-existing disposition in themind, whether permanent or temporary. A man brings his peculiar habitsof thought and feeling to the contemplation of objects, and the æstheticimpression produced is coloured by these predispositions. Thus, a personof a sad and gloomy cast of mind will be disposed to see a sombre beautywhere other eyes see nothing of the kind. And then there are all theeffects of temporary conditions of the imagination and the feelings. Thus, the individual mind may be focussed in a certain way through thesuggestion of another. People not seldom see a thing to be beautifulbecause they are told that it is so. It might not be well to inquire toocuriously how many of the frequenters of the annual art exhibitions usetheir own eyes in framing their æsthetic judgments. Or the temporarypredisposition may reside in a purely personal feeling or desireuppermost at the time. Our enjoyment of nature or of art is coloured byour temporary mood. There are moments of exceptional mentalexhilaration, when even a commonplace scene will excite an appreciablekind of admiration. Or there may be a strong wish to find a thingbeautiful begotten of another feeling. Thus, a lover desires to findbeauty in his mistress; or, having found it in her face and form, desires to find a harmonious beauty in her mind. In these different waystemporary accidents of personal feeling and imagination enter into anddetermine our æsthetic intuition, making it deviate from the commonstandard. This kind of error may even approximate in character to anhallucination of sense when there is nothing answering to a commonsource of æsthetic pleasure. Thus, the fond mother, through the veryforce of her affection, will construct a beauty in her child, which forothers is altogether non-existent. What applies to the perception of beauty in the narrow sense will applyto all other modes of æsthetic intuition, as that of the sublime and theludicrous, and the recognition of the opposite of beauty or the ugly. Inlike manner, it will apply to moral intuition in so far as it is aninstantaneous recognition of a certain quality in a perceived actionbased on, or at least conjoined with, a particular emotional effect. Inmen's intuitive judgments respecting the right and the wrong, the nobleand base, the admirable and contemptible, and so on, we may see the samekind of illusory universalizing of personal feeling as we have seen intheir judgments respecting the beautiful. And the sources of the errorare the same in the two cases. Accidents of experience, giving specialassociations to the actions, will not unfrequently warp the individualintuition. Ethical culture, like æsthetic culture, means a continualcasting aside of early illusory habits of intuition. And further, moralintuition illustrates all those effects of feeling which we have brieflytraced in the case of æsthetic intuition. The perversions of the moralintuition under the sway of prejudice are too familiar to need more thana bare allusion. _Nature of Insight. _ There remains one further mode of cognition which approximates incharacter to presentative knowledge, and is closely related to externalperception. I refer to the commonly called "intuitive" process by whichwe apprehend the feelings and thoughts of other minds through theexternal signs of movement, vocal sound, etc. , which make up expressionand language. This kind of knowledge, which is not sufficiently markedoff from external perception on the one side and introspection on theother, I venture to call Insight. I am well aware that this interpretation of the mental states of othersis commonly described as a process of inference involving a consciousreference to our own similar experiences. I willingly grant that it isoften so. At the same time, it must be perfectly plain that it is notalways so. It is, indeed, doubtful whether in its first stages in earlylife it is invariably so, for there seem to be good reasons forattributing to the infant mind a certain degree of instinctive orinherited capability in making out the looks and tones of others. [107]And, however this may be, it is certain that with the progress of life agood part of this interpretation comes to be automatic or unconscious, approximating in character to a sense-perception. To recognizecontentment in a placid smile is, one would say, hardly less immediateand intuitive than to recognize the coolness of a stream. We must, of course, all allow that the fusion of the presentative andthe representative element is, speaking generally, more complete in thecase of sense-perception than in that here considered. In spite ofBerkeley's masterly account of the _rationale_ of visual perception asan interpretation of "visual language" and all that has confirmed it, the plain man cannot, at the moment of looking at an object, easilybring himself to admit that distance is not directly present to hisvision. On the other hand, on cool reflection, he will recognize thatthe complacent benevolent sentiment is distinct from the particularmovements and changes in the eye and other features which express it. Yet, while admitting this, I must contend that there is no very hard andfast line dividing the two processes, but that the reading of others'feelings approximates in character to an act of perception. An intuitive insight may, then, be defined as that instantaneous, automatic, or "unconscious" mode of interpreting another's feelingwhich occurs whenever the feeling is fully expressed, and when its signsare sufficiently familiar to us. This definition will include theinterpretation of thoughts by means of language, though not, of course, the belief in an objective fact grounded on a recognition of another'sbelief. On the other hand, it will exclude all the more complexinterpretations of looks and words which imply conscious comparison, reflection, and reasoning. Further, it will exclude a large part of theinterpretation of actions as motived, since this, though sometimesapproaching the intuitive form, is for the most part a process ofconjectural or doubtful inference, and wanting in the immediateassurance which belongs to an intuitive reading of a present emotion orthought. From this short account of the process of insight, its relation toperception and introspection becomes pretty plain. On the one hand, itclosely resembles sense-perception, since it proceeds by theinterpretation of a sense-impression by means of a representative image. On the other hand, it differs from sense-perception, and is more closelyallied to introspection in the fact that, while the process ofinterpretation in the former case is a reconstruction of _external_experiences, in the latter case it is a reconstruction of _internal_experiences. To intuit another's feeling is clearly to represent toourselves a certain kind of internal experience previously known, in itselements at least, by introspection, while these represented experiencesare distinctly referred to another personality. And now we see what constitutes the object of insight. This is, in part, a common experience, as in the case of sense-perception and æstheticintuition, since to perceive another's feeling is implicitly to cognizethe external conditions of a common insight. But this is clearly not thewhole, nor even the main part of objective reality in this act ofcognition. An intuitive insight differs from a sense-perception in thatit involves an immediate assurance of the existence of a feelingpresentatively known, though not to our own minds. The object in insightis thus a presentative feeling as in introspection, though not our own, but another's. And so it differs from the object in sense-perception inso far as this last involves sense-experiences, as muscular and tactualfeelings, which are not _at the moment_ presentatively known to anymind. _Illusions of Insight. _ And now we are in a position, perhaps, to define an illusion of insight, and to inquire whether there is anything answering to our definition. Anillusory insight is a quasi-intuition of another's feelings which doesnot answer to the internal reality as presentatively known to thesubject himself. In spite of the errors of introspection dealt with inthe last chapter, nobody will doubt that, when it is a question betweena man's knowing what is at the moment in his own mind and somebodyelse's knowing, logic, as well as politeness, requires us to giveprecedence to the former. An illusion of insight, like the other varieties of illusion alreadydealt with, may arise either by way of wrong suggestion or by way of awarping preconception. Let us look at each of these sources apart. Our insights, like our perceptions, though intuitive in form, areobviously determined by previous experience, association, and habit. Hence, on its passive side, an illusion of insight may be described as awrong interpretation of a new or exceptional case. For example, havingassociated the representation of a slight feeling of astonishment withuplifted eyebrows, we irresistibly tend to see a face in which this is aconstant feature as expressing this particular shade of emotion. In thisway we sometimes fall into grotesque errors as to mental traits. And themost practised physiognomist may not unfrequently err by importing theresults of his special circle of experiences into new and unlike cases. Much the same thing occurs in language. Our timbre of voice, ourarticulation, and our vocabulary, like our physiognomy, have about themsomething individual, and error often arises from overlooking this, andhastily reading common interpretations into exceptional cases. Themisunderstandings that arise even among the most open and confidingfriends sufficiently illustrate this liability to error. Sometimes the error becomes more palpable, as, for example, when wevisit another country. A foreign language, when heard, provokinglysuggests all kinds of absurd meanings through analogies to our familiartongue. Thus, the Englishman who visits Germany cannot, for a time, heara lady use the expression, "Mein Mann, " without having the amusingsuggestion that the speaker is wishing to call special attention to thefact of her husband's masculinity. And doubtless the German who visitsus derives a similar kind of amusement from such involuntarycomparisons. A fertile source of illusory insight is, of course, conscious deceptionon the part of others. The rules of polite society require us to behypocrites in a small way, and we have occasionally to affect the signsof amiability, interest, and amusement, when our actual sentiment is oneof indifference, weariness, or even positive antipathy. And in this waya good deal of petty illusion arises. Although we may be well aware ofthe general untrustworthiness of this society behaviour, such is theforce of association and habit, that the bland tone and flattering wordirresistibly excite a momentary feeling of gratification, an effectwhich is made all the more easy by the co-operation of the recipient'sown wishes, touched on in the last chapter. Among all varieties of this deception, that of the stage is the mostcomplete. The actor is a man who has elaborately trained himself in thesimulation of certain feelings. And when his acting is of the bestquality, and the proper bodily attitude, gesture, tone of voice, and soon, are hit off, the force of the illusion completely masters us. Forthe moment we lose sight of the theatrical surroundings, and see theactor as really carried away by the passion which he so closelyimitates. Histrionic illusion is as complete as any artistic variety canventure to be. [108] I have said that our insights are limited by our own mental experience, and so by introspection. In truth, every interpretation of another'slook and word is determined ultimately, not by what we have previouslyobserved in others, but by what we have personally felt, or at leasthave in a sense made our own by intense sympathy. Hence we may, ingeneral, regard an illusion of insight on the active side as a hastyprojection of our own feelings, thoughts, etc. , into other minds. We habitually approach others with a predisposition to attribute to themour own modes of thinking and feeling. And this predisposition will bethe more powerful, the more desirous we are for sympathy, and for thatconfirmation of our own views which the reflection of another mindaffords. Thus, when making a new acquaintance, people are in generaldisposed to project too much of themselves into the person who is theobject of inspection. They intuitively endow him with their own ideas, ways of looking at things, prejudices of sentiment, and so on, andreceive something like a shock when later on they find out how differenthe is from this first hastily formed and largely performed image. The same thing occurs in the reading of literature, and the appreciationof the arts of expression generally. We usually approach an author witha predisposition to read our own habits of thought and sentiment intohis words. It is probably a characteristic defect of a good deal ofcurrent criticism of remote writers to attribute to them too much of ourmodern conceptions and aims. Similarly, we often import our own specialfeelings into the utterances of the poet and of the musical composer. That much of this intuition is illusory, may be seen by a littleattention to the "intuitions" of different critics. Two readers ofunlike emotional organization will find incompatible modes of feeling inthe same poet. And everybody knows how common it is for musical criticsand amateurs to discover quite dissimilar feelings in the samecomposition. [109] The effect of this active projection of personal feeling will, ofcourse, be seen most strikingly when there is a certain variety offeeling actually excited at the time in the observer's mind. A man whois in a particularly happy mood tends to reflect his exuberant gladnesson others. The lover, in the moment of exalted emotion, reads a responseto all his aspirations in his mistress's eyes. Again, a man will tend toproject his own present ideas into the minds of others, and so imaginethat they know what he knows; and this sometimes leads to a comical kindof embarrassment, and even to a betrayal of something which it was theinterest of the person to keep to himself. Once more, in interpretinglanguage, we may sometimes catch ourselves mistaking the meaning, owingto the presence of a certain idea in the mind at the time. Thus, if Ihave just been thinking of Comte, and overhear a person exclaim, "I'mpositive, " I irresistibly tend, for the moment, to ascribe to him anavowal of discipleship to the great positivist. _Poetic Illusion. _ The most remarkable example of this projection of feeling isundoubtedly illustrated in the poetic interpretation of inanimatenature. The personification of tree, mountain, ocean, and so on, illustrates, no doubt, the effect of association and externalsuggestion; for there are limits to such personification. Butresemblance and suggestion commonly bear, in this case, but a smallproportion to active constructive imagination. One might, perhaps, callthis kind of projection the hallucination of insight, since there isnothing objective corresponding to the interpretative image. The imaginative and poetic mind is continually on the look out for hintsof life, consciousness, and emotion in nature. It finds a certain kindof satisfaction in this half-illusory, dream-like transformation ofnature. The deepest ground of this tendency must probably be looked forin the primitive ideas of the race, and the transmission by inheritanceof the effect of its firmly fixed habits of mind. The undisciplined mindof early man, incapable of distinguishing the object of perception fromthe product of spontaneous imagination, and taking his own doubleexistence as the type of all existence, actually saw the stream, theocean, and the mountain as living beings; and so firmly rooted is thisway of regarding objects, that even our scientifically trained mindsfind it a relief to relapse occasionally into it. [110] While there is this general imaginative disposition in the poetic mindto endow nature with life and consciousness, there are specialtendencies to project the individual feelings into objects. Everyimaginative mind looks for reflections of its own deepest feelings inthe world about it. The lonely embittered heart, craving for sympathy, which he cannot meet with in his fellow-man, finds traces of it in thesighing of the trees or the moaning of the sad sea-wave. Our PoetLaureate, in his great elegy, has abundantly illustrated this impulse ofthe imagination to reflect its own emotional colouring on to inanimatethings: for example in the lines-- "The wild unrest that lives in woe Would dote and pore on yonder cloud That rises upward always higher, And onward drags a labouring breast, And topples round the dreary west, A looming bastion fringed with fire. " So far I have been considering active illusions of insight as arisingthrough the play of the impulse of the individual mind to project itsfeelings outwards, or to see their reflections in external things. Imust now add that active illusion may be due to causes similar to thosewhich we have seen to operate in the sphere of illusory perception andintrospection. That is to say, there may be a disposition, permanent ortemporary, to ascribe a certain kind of feeling to others in accordancewith our wishes, fears, and so on. To give an illustration of the permanent causes, it is well known that aconceited man will be disposed to attribute admiration of himself toothers. On the other hand, a shy, timid person will be prone to readinto other minds the opposite kind of feeling. Coming to temporary forces, we find that any expectation to meet with aparticular kind of mental trait in a new acquaintance will dispose theobserver hastily and erroneously to attribute corresponding feelings tothe person. And if this expectation springs out of a present feeling, the bias to illusory insight is still more powerful. For example, achild that fears its parent's displeasure will be prone to misinterpretthe parent's words and actions, colouring them according to its fears. So an angry man, strongly desirous of making out that a person hasinjured him, will be disposed to see signs of conscious guilt in thisperson's looks or words. Similarly, a lover will read fine thoughts orsentiments into the mind of his mistress under the influence of a strongwish to admire. And what applies to the illusory interpretation of others' feelingsapplies to the ascription of feelings to inanimate objects. This is duenot simply to the impulse to expand one's conscious existence throughfar-reaching resonances of sympathy, but also to a permanent ortemporary disposition to attribute a certain kind of feeling to anobject. Thus, the poet personifies nature in part because his emotionalcravings prompt him to construct the idea of something that can beadmired or worshipped. Once more, the action of a momentary feeling whenactually excited is seen in the "mechanical" impulse of a man toretaliate when he strikes his foot against an object, as a chair, whichclearly involves a tendency to attribute an intention to hurt to theunoffending body, and the _rationale_ of which odd procedure is prettycorrectly expressed in the popular phrase: "It relieves the feelings. " It is worth noting, perhaps, that these illusions of insight, like thoseof perception, may involve an inattention to the actual impression ofthe moment. To erroneously attribute a feeling to another through anexcess of sympathetic eagerness is often to overlook what a perfectlydispassionate observer would see, as, for example, the immobility of thefeatures or the signs of a deliberate effort to simulate. Thisinattention will, it is obvious, be greatest in the poetic attributionof life and personality to natural objects, in so far as thisapproximates to a complete momentary illusion. To see a dark overhangingrock as a grim sombre human presence, is for the moment to view it underthis aspect only, abstracting from its many obvious unlikenesses. In the same manner, a tendency to read a particular meaning into a wordmay lead to the misapprehension of the word. To give an illustration: Iwas lately reading the fifth volume of G. H. Lewes's _Problems of Lifeand Mind_. In reading the first sentence of one of the sections, I againand again fell into the error of taking "The great Lagrange, " for "Thegreat Language. " On glancing back I saw that the section was headed "OnLanguage, " and I at once recognized the cause of my error in thepre-existence in my mind of the representative image of the word"language. " In concluding this short account of the errors of insight, I may observethat their range is obviously much greater than that of the previouslyconsidered classes of presentative illusion. This is, indeed, involvedin what has been said about the nature of the process. Insight, as wehave seen, though here classed with preservative cognition, occupies akind of border-land between immediate knowledge or intuition andinference, shading off from the one to the other. And in the very natureof the case the scope for error must be great. Even overlooking humanreticence, and, what is worse, human hypocrisy, the conditions of anaccurate reading of others' minds are rarely realized. If, as has beenremarked by a good authority, one rarely meets, even among intelligentpeople, with a fairly accurate observer of external things, what shallbe said as to the commonly claimed power of "intuitive insight" intoother people's thoughts and feelings, as though it were a process abovesuspicion? It is plain, indeed, on a little reflection, that, takinginto account what is required in the way of large and varied experience(personal and social), a habit of careful introspection, as well as ahabit of subtle discriminative attention to the external signs of mentallife, and lastly, a freedom from prepossession and bias, only a very fewcan ever hope even to approximate to good readers of character. And then we have to bear in mind that this large amount of error is aptto remain uncorrected. There is not, as in the case of externalperception, an easy way of verification, by calling in another sense; amisapprehension, once formed, is apt to remain, and I need hardly saythat errors in these matters of mutual comprehension have their palpablepractical consequences. All social cohesion and co-operation rest onthis comprehension, and are limited by its degree of perfection. Nay, more, all common knowledge itself, in so far as it depends on a mutualcommunication of impressions, ideas, and beliefs, is limited by thefact of this great liability to error in what at first seems to be oneof the most certain kinds of knowledge. In view of this depressing amount of error, our solace must be found inthe reflection that this seemingly perfect instrument of intuitiveinsight is, in reality, like that of introspection, in process of beingfashioned. Mutual comprehension has only become necessary since manentered the social state, and this, to judge by the evolutionist'smeasure of time, is not so long ago. A mental structure so complex anddelicate requires for its development a proportionate degree ofexercise, and it is not reasonable to look yet for perfect precision ofaction. Nevertheless, we may hope that, with the advance of socialdevelopment, the faculty is continually gaining in precision andcertainty. And, indeed, this hope is already assured to us in the factthat the faculty has begun to criticise itself, to distinguish betweenan erroneous and a true form of its-operation. In fact, all that hasbeen here said about illusions of insight has involved the assumptionthat intellectual culture sharpens the power and makes it less liable toerr. CHAPTER X. ILLUSIONS OF MEMORY. Thus far we have been dealing with Presentative Illusions, that is tosay, with the errors incident to the process of what may roughly becalled presentative cognition. We have now to pass to the considerationof Representative Illusion, or that kind of error which attendsrepresentative cognition in so far as it is immediate orself-sufficient, and not consciously based on other cognition. Of suchimmediate representative cognition, memory forms the most conspicuousand most easily recognized variety. Accordingly, I proceed to take upthe subject of the Illusions of Memory. [111] The mystery of memory lies in the apparent immediateness of the mind'scontact with the vanished past. In "looking back" on our life, we seemto ourselves for the moment to rise above the limitations of time, toundo its work of extinction, seizing again the realities which itson-rushing stream had borne far from us. Memory is a kind ofresurrection of the buried past: as we fix our retrospective glance onit, it appears to start anew into life; forms arise within our mindswhich, we feel sure, must faithfully represent the things that were. Wedo not ask for any proof of the fidelity of this dramatic representationof our past history by memory. It is seen to be a faithful imitation, just because it is felt to be a revival of the past. To seek to make theimmediate testimony of memory more sure seems absurd, since all our waysof describing and illustrating this mental operation assume that in thevery act of performing it we do recover a part of our seemingly "deadselves. " To challenge the veracity of a person's memory is one of the boldestthings one can do in the way of attacking deep-seated conviction. Memoryis the peculiar domain of the individual. In going back in recollectionto the scenes of other years he is drawing on the secret store-house ofhis own consciousness, with which a stranger must not intermeddle. Tocast doubt on a person's memory is commonly resented as an impertinence, hardly less rude than to question his reading of his own present mentalstate. Even if the challenger professedly bases his challenge on thetestimony of his own memory, the challenged party is hardly likely toallow the right of comparing testimonies. He can in most cases boldlyassert that those who differ from him are lacking in _his_ power ofrecollection. The past, in becoming the past, has, for most people, ceased to be a common object of reference; it has become a part of theindividual's own inner self, and cannot be easily dislodged or shaken. Yet, although people in general are naturally disposed to be veryconfident about matters of recollection, reflective persons are prettysure to find out, sooner or later, that they occasionally fall intoerrors of memory. It is not the philosopher who first hints at themendacity of memory, but the "plain man" who takes careful note of whatreally happens in the world of his personal experience. Thus, we hearpersons, quite innocent of speculative doubt, qualifying an assertionmade on personal recollection by the proviso, "unless my memory hasplayed me false. " And even less reflective persons, including many whopride themselves on their excellent memory, will, when sorely pressed, make a grudging admission that they may, after all, be in error. Perhapsthe weakest degree of such an admission, and one which allows to theconceding party a semblance of victory, is illustrated in the "lastword" of one who has boldly maintained a proposition on the strength ofindividual recollection, but begins to recognize the instability of hisposition: "I either witnessed the occurrence or dreamt it. " This issufficient to prove that, with all people's boasting about theinfallibility of memory, there are many who have a shrewd suspicion thatsome of its asseverations will not bear a very close scrutiny. _Psychology of Memory. _ In order to understand the errors of memory, we must proceed, as in thecase of illusions of perception, by examining a little into the natureof the normal or correct process. An act of recollection is said by the psychologist to be purelyrepresentative in character, whereas perception is partlyrepresentative, partly preservative. To recall an object to the mind isto reconstruct the percept in the absence of a sense-impression. [112] An act of memory is obviously distinguished from one of simpleimagination by the presence of a conscious reference to the past. Everyrecollection is an immediate reapprehension of some past object orevent. However vague this reference may be, it must be there toconstitute the process one of recollection. The every-day usages of language do not at first sight seem toconsistently observe this distinction. When a boy says, "I remember mylesson, " he appears to be thinking of the present only, and notreferring to the past. In truth, however, there is a vague reference tothe fact of retaining a piece of knowledge through a given interval oftime. Again, when a man says, "I recollect your face, " this means, "Your faceseems familiar to me. " Here again, though there is no definite referenceto the past, there is a vague and indefinite one. It is plain from this definition that recollection is involved in allrecognition or identification. Merely to be aware that I have seen aperson before implies a minimum exercise of memory. Yet we may roughlydistinguish the two actions of perception and recollection in theprocess of recognition. The mere recognition of an object does notimply the presence of a distinct representative or mnemonic image. Inpoint of fact, in so far as recognition is assimilation, it cannot besaid to imply a _distinct_ act of memory at all. It is only whensimilarity is perceived amid difference, only when the accompaniments orsurroundings of the object as previously seen, differencing it from theobject as now seen, are brought up to the mind that we may be saiddistinctly to recall the past. And our state of mind in recognizing anobject or person is commonly an alternation between these two acts ofseparating the mnemonic image from the percept and so recalling orrecollecting the past, and fusing the image and the percept in what isspecifically marked off as recognition. [113] Although I have spoken of memory as a reinstatement in representativeform of external experience, the term must be understood to includeevery revival of a past experience, whether external or internal, whichis recognized as a revival. In a general way, the recallings of ourinternal feelings take place in close connection with the recollectionof external circumstances or events, and so they may be regarded aslargely conditioned by the laws of this second kind of reproduction. The old conceptions of mind, which regarded every mental phenomenon as amanifestation of an occult spiritual substance, naturally led to thesupposition that an act of recollection involves the continued, unbroken existence of the reproductive or mnemonic image in the hiddenregions of the mind. To recollect is, according to this view, to drawthe image out of the dark vaults of unconscious mind into the upperchamber of illumined consciousness. Modern psychology recognizes no such pigeonhole apparatus in unconsciousmind. On the purely psychical side, memory is nothing but an occasionalreappearance of a past mental experience. And the sole mental conditionsof this reappearance are to be found in the circumstances of the momentof the original experience and in those of the moment of thereappearance. Among these are to be specially noted, first of all, the degree ofimpressiveness of the original experience, that is to say, the amount ofinterest it awakened and of attention it excited. The more impressiveany experience, the greater the chances of its subsequent revival. Moreover, the absence of impressiveness in the original experience maybe made good either by a repetition of the actual experience or, in thecase of non-recurring experiences, by the fact of previous mnemonicrevivals. In the second place, the pre-existing mental states at the time ofrevival are essential conditions. It is now known that everyrecollection is determined by some link of association, that everymnemonic image presents itself in consciousness only when it has beenpreceded by some other mental state, presentative or representative, which is related to the image. This relation may be one of contiguity, that is to say, the original experiences may have occurred at the sametime or in close succession; or one of similarity (partial and notamounting to identity), as where the sight of one place or personrecalls that of another place or person. Finally, it is to be observedthat recollection is often an act, in the full sense of that term, involving an effort of voluntary attention at the moment of revival. Modern physiology has done much towards helping us to understand thenervous conditions of memory. The biologist regards memory as a specialphase of a universal property of organic structure, namely, modifiability by the exercise of function, or the survival after anyparticular kind of activity of a disposition to act again in thatparticular way. The revival of a mental impression in the weaker form ofan image is thus, on its physical side, due in part to this remainingfunctional disposition in the central nervous tracts concerned. And so, while on the psychical or subjective side we are unable to find anythingpermanent in memory, on the physical or objective side we do find such apermanent substratum. With respect to the special conditions of mnemonic revival at any time, physiology is less explicit. In a general way, it informs us that such areinstatement of the past is determined by the existence of certainconnections between the nervous structures concerned in the reviving andrevived mental elements. Thus, it is said that when the sound of a namecalls up in the mind a visual image of a person seen some time since, itis because connections have been formed between particular regions andmodes of activity of the auditory and the visual centres. And it issupposed that the existence of such connections is somehow due to thefact that the two regions acted simultaneously in the first instance, when the sight of the person was accompanied by the hearing of his name. In other words, the centres, as a whole, will tend to act at any futuremoment in the same complex way in which they have acted in past moments. All this is valuable hypothesis so far as it goes, though it plainlyleaves much unaccounted for. As to why this reinstatement of a totalcerebral pulsation in consequence of the re-excitation of a portion ofthe same should be accompanied by the specific mode of consciousnesswhich we call recollection of something past, it is perhaps unreasonableto ask of physiology any sort of explanation. [114] Thus far as to the general or essential characteristics of memory on itsmental and its bodily side. But what we commonly mean by memory is, onits psychical side at least, much more than this. We do not say that weproperly recollect a thing unless we are able to refer it to some moreor less clearly defined region of the past, and to localize it in thesuccession of experiences making up our mental image of the past. Inother words, though we may speak of an imperfect kind of recollectionwhere this definite reference is wanting, we mean by a perfect form ofmemory something which includes this reference. Without entering just now upon a full analysis of what this reference toa particular region of the past means, I may observe that it takes placeby help of an habitual retracing of the past, or certain portions of it, that is to say, a regressive movement of the imagination along the linesof our actual experience. Setting out from the present moment, I canmove regressively to the preceding state of consciousness, to thepenultimate, and so on. The fact that each distinct mental state iscontinuous with the preceding and the succeeding, and in a certain senseoverlaps these, makes any portion of our experience essentially asuccession of states of consciousness, involving some rudimentary ideaof time. And thus, whether I anticipate a future event or recall a pastone, my imagination, setting out from the present moment, constructs asequence of experiences of which the one particularly dwelt on is theother term or boundary. And our idea of the position of this last intime, like that of an object in space, is one of a relation to ourpresent position, and is determined by the length of the sequence ofexperiences thus run over by the imagination. [115] It may be added thatsince the imagination can much more easily follow the actual order ofexperience than conceive it as reversed, the retrospective act of memorynaturally tends to complete itself by a return movement forwards fromthe remembered event to the present moment. In practice this detailed retracing of successive moments of mental lifeis confined to very recent experiences. If I try to localize in time aremote event, I am content with placing it in relation to a series ofprominent events or landmarks which serves me as a rough scheme of thepast. The formation of such a mnemonic framework is largely due to theneeds of social converse, which proceeds by help of a common standard ofreference. This standard is supplied by those objective, that is to say, commonly experienced regularities of succession which constitute thenatural and artificial divisions of the years, seasons, months, weeks, etc. The habit of recurring to these fixed divisional points of the pastrenders a return of imagination to any one of them more and more easy. Aman has a definite idea of "a year ago" which the child wants, justbecause he has had so frequently to execute that vague regressivemovement by which the idea arises. And though, as our actual point intime moves forward, the relative position of any given landmark iscontinually changing, the change easily adapts itself to that scheme oftime-divisions which holds good for any present point. Few of our recollections of remote events involve a definite referenceto this system of landmarks. The recollections of early life are, in thecase of most people, so far as they depend on individual memory, veryvaguely and imperfectly localized. And many recent experiences which aresaid to be half forgotten, are not referred to any clearly assignableposition in time. One may say that in average cases definitelocalization characterizes only such supremely interesting personalexperiences as spontaneously recur again and again to the mind. For therest it is confined to those facts and events of general interest towhich our social habits lead us repeatedly to go back. [116] The consciousness of personal identity is said to be bound up withmemory. That is to say, I am conscious of a continuous permanent selfunder all the varying surface-play of the stream of consciousness, justbecause I can, by an act of recollection, bring together any twoportions of this stream of experience, and so recognize the unbrokencontinuity of the whole. If this is so, it would seem to follow from thevery fragmentary character of our recollections that our sense ofidentity is very incomplete. As we shall see presently, there is goodreason to look upon, this consciousness of continuous personal existenceas resting only in part on memory, and mainly on our independentlyformed representation of what has happened in the numberless and oftenhuge lacunæ of the past left by memory. Having thus a rough idea of the mechanism of memory to guide us, we maybe able to investigate the illusions incident to the process. _Illusions of Memory. _ By an illusion of memory we are to understand a false recollection or awrong reference of an idea to some region of the past. It might, perhaps, be roughly described as a wrong interpretation of a specialkind of mental image, namely, what I have called a mnemonic image. Mnemonic illusion is thus distinct from mere forgetfulness or imperfectmemory. To forget or be doubtful about a past event is one thing; toseem to ourselves to remember it when we afterwards find that the factwas otherwise than we represented it in the apparent act of recollectionis another thing. Indistinctness of recollection, or the decay ofmemory, is, as we shall soon see, an important co-operant condition ofmnemonic illusion, but does not constitute it, any more than haziness ofvision or disease of the visual organ, though highly favourable tooptical illusion, can be said to constitute it. We may conveniently proceed in our detailed examination of illusions ofmemory, by distinguishing between three facts which appear to beinvolved in every complete and accurate process of recollection. When Idistinctly recall an event, I am immediately sure of three things: (1)that something did really happen to me; (2) that it happened in the wayI now think; and (3) that it happened when it appears to have happened. I cannot be said to recall a past event unless I feel sure on each ofthese points. Thus, to be able to say that an event happened at aparticular date, and yet unable to describe how it happened, means thatI have a very incomplete recollection. The same is true when I canrecall an event pretty distinctly, but fail to assign it its properdate. This being so, it follows that there are three possible openings, and only three, by which errors of memory may creep in. And, as a matterof fact, each of these openings will be found to let in one class ofmnemonic illusion. Thus we have (1) false recollections, to which therecorrespond no real events of personal history; (2) others whichmisrepresent the manner of happening of the events; and (3) others whichfalsify the date of the events remembered. It is obvious, from a mere glance at this threefold classification, thatillusions of memory closely correspond to visual illusions. Thus, class(1) may be likened to the optical illusions known as subjectivesensations of light, or ocular spectra. Here we can prove that there isnothing actually seen in the field of vision, and that the semblance ofa visible object arises from quite another source than that of ordinaryexternal light-stimulation, and by what may be called an accident. Similarly, in the case of the first class of mnemonic illusions, weshall find that there is nothing actually recollected, but that themnemonic spectra or phantoms of recollected objects can be accounted forin quite another way. Such illusions come nearest to hallucinations inthe region of memory. Again, class (2) has its visual analogue in those optical illusionswhich depend on effects of haziness and of the action of refractingmedia interposed between the eye and the object; in which cases, thoughthere is some real thing corresponding to the perception, this is seenin a highly defective, distorted, and misleading form. In like manner, we can say that the images of memory often get obscured, distorted, andotherwise altered when they have receded into the dim distance, and arelooked back upon through a long space of intervening mental experience. Finally, class (3) has its visual counterpart in erroneous perceptionsof distance, as when, for example, owing to the clearness of themountain atmosphere and the absence of intervening objects, the side ofthe Jungfrau looks to the inexperienced tourist at Wengernalp hardlyfurther than a stone's throw. It will be found that when our memoryfalsifies the date of an event, the error arises much in the same way asa visual miscalculation of distance. This threefold division of illusions of memory is plainly a rathersuperficial one, and not based on distinctions of psychological natureor origin. In order to make our treatment of the subject scientific aswell as popular, it will be necessary to introduce the distinctionbetween the passive and the active factor under each head. It will befound, I think, without forcing the analogy too far, that here, as inthe case of the illusions of perception and introspection, error isattributable now to misleading suggestion on the part of the mentalcontent of the moment, now to a process of incorporating into thiscontent a mental image not suggested by it, but existing independently. If we are to proceed as we did in the case of the illusions of sense, and take up the lower stages of error first of all, we shall need tobegin with the third class of errors, those of localization in time, orof what may be called mnemonic perspective. It has been already observedthat the definite localization of a mnemonic image is only an occasionalaccompaniment of what is loosely called recollection. Hence, error asto the position of an event in the past chain of events would seem toinvolve the least degree of violation of the confidence which we arewont to repose in memory. After this, we may proceed to the discussionof the second class, which I may call distortions of the mnemonicpicture. And, finally, we may deal with the most signal and palpablevariety of error of memory, namely, the illusions which I have calledmnemonic spectra. _Illusions of Perspective: A. Definite Localization. _ In order to understand these errors of mnemonic perspective, we shallhave to inquire more closely than we have yet done into thecircumstances which customarily determine our idea of the degree ofpropinquity or of remoteness of a past event. And first of all, we willtake the case of a complete act of recollection when the mind is able totravel back along an uninterrupted series of experiences to a definitelyapprehended point. Here there would seem, at first sight, to be no roomfor error, since this movement of retrospective imagination may be saidto involve a direct measurement of the distance, just as a sweep of theeye over the ground between a spectator and an object affords a directmeasurement of the intervening space. Modern science, however, tells us that this mode of measurement is by nomeans the simple and accurate process which it at first seems to be. Inpoint of fact, there is something like a constant error in all suchretrospective measurement. Vierordt has proved experimentally, by makinga person try to reproduce the varying time-intervals between thestrokes of the pendulum of a metronome, that when the interval is a verysmall one, we uniformly tend to exaggerate it in retrospection; when alarge one, to regard it, on the contrary, as less than it actuallywas. [117] A mere act of reflection will convince any one that when he tries toconceive a very small interval, say a quarter of a second, he is likelyto make it too great. On the other hand, when we try to conceive a year, we do not fully grasp the whole extent of the duration. This is provedby the fact that merely by spending more time over the attempt, and sorecalling a larger number of the details of the period, we veryconsiderably enlarge our first estimate of the duration. And this leadsto great discrepancies in the appreciation of the relative magnitudes ofpast sections of time. Thus, as Wundt observes, though in retrospectboth a month and a year seem too short, the latter is relatively muchmore shortened than the former. [118] The cause of this constant error in the mode of reproducing durationsseems to be connected with the very nature of the reproductive act. Itmust be borne in mind that this act is itself, like the experience whichit represents, a mental process, occupying time, and that consequentlyit may very possibly reflect its time-character on the resultingjudgment. Thus, since it certainly takes more than a quarter of a secondto pass in imagination from one impression to another, it may be that wetend to confound this duration with that which we try to represent. Similarly, the fact that in the act of reproductive imagination weunder-estimate a longer interval between two impressions, say those ofthe slow beats of a colliery engine, may be accounted for by thesupposition that the imagination tends to pass from the one impressionto the succeeding one too rapidly. [119] The gross misappreciation of duration of long periods of time, while itmay illustrate the principle just touched on, clearly involves theeffect of other and more powerful influences. A mere glance at what isin our mind when we recall such a period as a month or a year, showsthat there is no clear concrete representation at all. Time, it has beenoften said, is known only so far as filled with concrete contents orconscious experiences, and a perfect imagination of any particularperiod of past time would involve a retracing of all the successiveexperiences which have gone to make up this section of our life. This, Ineed not say, never happens, both because, on the one hand, memory doesnot allow of a complete reproduction of any segment of our experience, and because, on the other hand, such an imaginative reproduction, evenif possible, would clearly occupy as much time as the experienceitself. [120] When I call up an image of the year just closing, what really happens isa rapid movement of imagination over a series of prominent events, amongwhich the succession of seasons probably occupies the foremost place, serving, as I have remarked, as a framework for my retrospectivepicture. Each of the events which I thus run over is really a longsuccession of shorter experiences, which, however, I do not separatelyrepresent to myself. My imaginative reproduction of such a period isthus essentially a greatly abbreviated and symbolic mode ofrepresentation. It by no means corresponds to the visual imagination ofa large magnitude, say that of the length of sea horizon visible at anyone moment, which is complete in an instant, and quite independent of asuccessive imagination of its parts or details. It is essentially a veryfragmentary and defective numerical idea, in which, moreover, the realquantitative value of the units is altogether lost sight of. Now, it seems to follow from this that there is something illusory inall our recallings of long periods of the past. It is by no meansstrictly correct to say that memory ever reinstates the past. It is moretrue to say that we see the past in retrospect as greatly foreshortened. Yet even this is hardly an accurate account of what takes place, since, when we look at an object foreshortened in perspective, we see enough toenable us imaginatively to reconstruct the actual size of the object, whereas in the case of time-perspective no such reconstruction is evenindirectly possible. It is to be added that this constant error in time-reproduction isgreater in the case of remote periods than of near ones of the samelength. Thus, the retrospective estimate of a duration far removed fromthe present, say the length of time passed at a particular school, ismuch more superficial and fragmentary than that of a recentcorresponding period. So that the time-vista of the past is seen toanswer pretty closely to a visible perspective in which the amount ofapparent error due to foreshortening increases with the distance. In practice, however, this defect in the imagination of duration leadsto no error. Although, as a concrete image answering to some definitesuccession of experiences a year is a gross misrepresentation, as ageneral concept implying a collection of a certain number of similarsuccessions of experience it is sufficiently exact. That is to say, though we cannot imagine the _absolute_ duration of any such cycle ofexperience, we can, by the simple device of conceiving certain durationsas multiples of others, perfectly well compare different periods oftimes, and so appreciate their _relative_ magnitudes. Leaving, then, this constant error in time-appreciation, we will pass tothe variable and more palpable errors in the retrospective measurementof time. Each person's experience will have told him that in estimatingthe distance of a past event by a mere retrospective sense of duration, he is liable to extraordinary fluctuations of judgment. Sometimes whenthe clock strikes we are surprised at the rapidity of the hour. At othertimes the timepiece seems rather to have lagged behind its usual pace. And what is true of a short interval is still more true of longerintervals, as months and years. The understanding of these fluctuationswill be promoted by our brief glance at the constant errors inretrospective time-appreciation. And here it is necessary to distinguish between the sense of durationwhich we have during any period, and the retrospective sense whichsurvives the period, for these do not necessarily agree. The formerrests mainly on our prospective sense of time, whereas the latter mustbe altogether retrospective. [121] Our estimate of time as it passes is commonly said to depend on theamount of consciousness which we are giving to the fact of itstransition. Thus, when the mind is unoccupied and suffering from_ennui_, we feel time to move sluggishly. On the other hand, interestingemployment, by diverting the thoughts from time, makes it appear to moveat a more rapid pace. This fact is shown in the common expressions whichwe employ, such as "to kill time, " and the German _Langweile_. Similarly, it is said that when we are eagerly anticipating an event, asthe arrival of a friend, the mere fact of dwelling on the interval makesit appear to swell out. [122] This view is correct in the main, and is seen, indeed, to follow fromthe great psychological principle that what we attend to exists for usmore, has more reality, and so naturally seems greater than what we donot attend to. At the same time, this principle must be supplemented byanother consideration. Suppose that I am very desirous that time shouldnot pass quickly. If, for example, I am enjoying myself or indulging inidleness, and know that I have to be off to keep a not very agreeableengagement in a quarter of an hour, time will seem to pass too rapidly;and this not because my thoughts are diverted from the fact of itstransition, for, on the contrary, they are reverting to it more thanthey usually do, but because my wish to lengthen the interval leads meto represent the unwelcome moment as further off than it actually is, inother words, to construct an ideal representation of the period incontrast with which the real duration looks miserably short. Our estimate of duration, when it is over, depends less on thiscircumstance of having attended to its transition than on otherconsiderations. Wundt, indeed, seems to think that the feelingaccompanying the actual flow of time has no effect on the survivingsubjective appreciation; but this must surely be an error, since ourmental image of any period is determined by the character of itscontents. Wundt says that when once a tedious waiting is over, it looksshort because we instantly forget the feeling of tedium. Myself-observation, as well as the interrogation of others, has satisfiedme, on the contrary, that this feeling distinctly colours theretrospective appreciation. Thus, when waiting at a railway station fora belated train, I am distinctly aware that each quarter of an hourlooks long, not only as it passes, but when it is over. In fact, I amdisposed to express my feeling as one of disappointment that only soshort an interval has passed since I last looked at my watch. Nevertheless, I am ready to allow that, though a feeling of tedium, orthe contrary feeling of irritation at the rapidity of time, will lingerfor an appreciable interval and colour the retrospective estimate oftime, this backward view is chiefly determined by other considerations. As Wundt remarks, we have no sense of time's slowness during sleep, yeton waking we imagine that we have been dreaming for an immensely longperiod. This retrospective appreciation is determined by the number andthe degree or intensity of the experiences, and, what comes very much tothe same thing, by the amount of unlikeness, freshness, anddiscontinuity characterizing these experiences. Time, as I have already hinted, is known under the form of a successionof different conscious experiences. Unbroken uniformity would give us nosense of time, because it would give us no conscious experience at all. Strictly speaking, there is no such thing as a perfectly uniform mentalstate extending through an appreciable duration. In looking at one andthe same object, even in listening to one and the same tone, I am in notwo successive fractions of a second in exactly the same state of mind. Slight alterations in the strength of the sensation, [123] in the degreeor direction of attention, and in the composition of that penumbra ofvague images which it calls up, occur at every distinguishable fractionof time. This being so, it would seem to follow that the greater the number ofclearly marked changes, and the more impressive and exciting thesetransitions, the fuller will be our sense of time. And this is borne outby individual reflection. When striking and deeply interesting eventsfollow one another very rapidly, as when we are travelling, durationappears to swell out. It is possible that such a succession of stirring experiences may begeta vague consciousness of time at each successive moment, and apart fromretrospection, simply by force of the change. In other words, withoutour distinctly attending to time, a series of novel impressions might, by giving us the consciousness of change, make us dimly aware of thenumerical richness of our experiences. But, however this be, there is nodoubt that, in glancing back on such a succession of excitingtransitions of mental condition, time appears to expand enormously, justas it does in looking back on our dream-experience, or that rapid seriesof intensified feelings which, according to De Quincey and others, isproduced by certain narcotics. The reason of this is plain. Such a type of successive experience offersto the retrospective imagination a large number of distinguishablepoints, and since this mode of estimating time depends, as we have seen, on the extent of the process of filling in, time will necessarily appearlong in this case. On the other hand, when we have been engaged in veryordinary pursuits, in which few deeply interesting or exciting eventshave impressed themselves on memory, our retrospective picture willnecessarily be very much of a blank, and consequently the duration ofthe period will seem to be short. I observed that this retrospective appreciation of time depended on thedegree of connection between the successive experiences. This conditionis very much the same as the other just given, namely, the degree ofuniformity of the experiences, since the more closely the successivestages of the experience are connected--as when, for example, we aregoing through our daily routine of work--the more quiet and unexcitingwill be the transition from each stage to its succeeding one. And on theother hand, all novelty of impression and exciting transition ofexperience clearly involves a want of connection. Wundt thinks theretrospective estimate of a connected series of experiences, such asthose of our daily round of occupations, is defective just because theeffort of attention, which precedes even an imaginative reproduction ofan impression, so quickly accommodates itself in this case to each ofthe successive steps, whereas, when the experiences to be recalled aredisconnected, the effort requires more time. In this way, the estimateof a past duration would be coloured by the sense of time accompanyingthe reproductive process itself. This may very likely be the case, yet Ishould be disposed to attach most importance to the number ofdistinguishable items of experience recalled. Our representation of the position of a given event in the past is, as Ihave tried to show, determined by the movement of imagination in goingback to it from the present. And this is the same thing as to say thatit depends on our retrospective sense of the intervening space. That isto say, the sense of distance in time, as in space, is the recognitionof a term to a movement. And just as the distance of an object will seemgreater when there are many intervening objects affording points ofmeasurement, than when there are none (as on the uniform surface of thesea), so the distance of an event will vary with the number ofrecognized intervening points. The appreciation of the distance of an event in time does not, however, wholly depend on the character of this movement of imagination. Just asthe apparent distance of a visible object depends _inter alia_ on thedistinctness of the retinal impression, so the apparent temporalremoteness of a past event depends in part on the degree of intensityand clearness of the mnemonic image. This is seen even in the case ofthose images which we are able distinctly to localize in thetime-perspective. For a series of exciting experiences interveningbetween the present and a past event appears not only _directly_ to addto our sense of distance by constituting an apparently long interval, but _indirectly_ to add to it by giving an unusual degree of faintnessto the recalled image. An event preceding some unusually stirring seriesof experiences gets thrust out of consciousness by the very engrossingnature of the new experiences, and so tends to grow more faint andghost-like than it would otherwise have done. The full force of this circumstance is best seen in the fact that a veryrecent event, bringing with it a deep mental shock and a rapid stirringof wide tracts of feeling and thought, may get to look old in amarvellously short space of time. An announcement of the loss of a dearfriend, when sudden and deeply agitating, will seem remote even after anhour of such intense emotional experience. And the same twofoldconsideration probably explains the well-known fact that a year seemsmuch shorter to the adult than to the child. The novel and comparativelyexciting impressions of childhood tend to fill out time in retrospect, and also to throw back remote events into a dimly discernible region. Now, this same circumstance, the degree of vividness or of faintness ofthe mnemonic image, is that which determines our idea of distance whenthe character of the intervening experiences produces no appreciableeffect. [124] This is most strikingly illustrated in those imperfectkinds of recollection in which we are unable to definitely localize themnemonic image. To the consideration of these we will now turn. B. _Indefinite Localization. _ Speaking roughly and generally, we may say that the vividness of animage of memory decreases in proportion as the distance of the eventincreases. And this is the rule which we unconsciously apply indetermining distance in time. Nevertheless, this rule gives us by nomeans an infallible criterion of distance. The very fact that differentpeople so often dispute about the dates and the order of past eventsexperienced in common, shows pretty plainly that images of the same agetend to arise in the mind with very unequal degrees of vividness. Sometimes pictures of very remote incidents may suddenly presentthemselves to our minds with a singular degree of brightness and force. And when this is the case, there is a disposition to think of them asnear. If the relations of the event to other events preceding andsucceeding it are not remembered, this momentary illusion will persist. We have all heard persons exclaim, "It seems only yesterday, " under thesense of nearness which accompanies a recollection of a remote eventwhen vividly excited. The most familiar instance of such livelyreproduction is the feeling which we experience on revisiting the sceneof some memorable event. At such a time the past may return withsomething of the insistence of a present perceived reality. In passingfrom place to place, in talking with others, and in reading, we areliable to the sudden return by hidden paths of association of images ofincidents that had long seemed forgotten, and when they thus start upfresh and vigorous, away from their proper surroundings, they invariablyinduce a feeling of the propinquity of the events. In many cases we cannot say why these particular images, long buried inoblivion, should thus suddenly regain so much vitality. There seems, indeed, to be almost as much that is arbitrary and capricious in theselection by memory of its vivid images as in the selection of itsimages as a whole; and, this being so, it is plain that we are greatlyexposed to the risk of illusion from this source. There is an opposite effect in the case of recent occurrences that, forsome reason or another, have left but a faint impression on the memory;though this fact is not, perhaps, so familiar as the other. I met afriend, we will suppose, a few days since at my club, and we exchanged afew words. My mind was somewhat preoccupied at the time, and theoccurrence did not stamp itself on my recollection. To-day I meet himagain, and he reminds me of a promise I made him at the time. Hisreminder suffices to restore a dim image of the incident, but the factof its dimness leads to the illusion that it really happened much longerago, and it is only on my friend's strong assurances, and on reasoningfrom other data that it must have occurred the day he mentions, that Iam able to dismiss the illusion. The most striking examples of the illusory effect of mere vividness, involving a complete detachment of the event from the prominentlandmarks of the past, are afforded by public events which lie outsidethe narrower circle of our personal life, and which do not in thenatural course of things become linked to any definitely localizedpoints in the field of memory. These events may be very stirring andengrossing for the time, but in many cases they pass out of the mindjust as suddenly as they entered it. We have no occasion to revert tothem, and if by chance we are afterwards reminded of them, they arepretty certain to look too near, just because the fact of their havinggreatly interested us has served to render their images particularlyvivid. A curious instance of this illusory effect was supplied not long sinceby the case of the ex-detectives, the expiration of whose term ofpunishment (three years) served as an occasion for the newspapers torecall the event of their trial and conviction. The news that threeyears had elapsed since this well-remembered occurrence proved verystartling to myself, and to a number of my friends, all of us agreeingthat the event did not seem to be at more than a third of its realdistance. More than one newspaper commented on the apparent rapidity ofthe time, and this shows pretty plainly that there was some cause atwork, such as I have suggested, producing a common illusion. I have treated of these illusions connected with the estimate of pasttime and the dating of past events as passive illusions, not involvingany active predisposition on the part of the imagination. At the sametime, it is possible that error in these matters may occasionally dependon a present condition of the feelings and the imagination. It seemsplain that since the apparent degree of remoteness of an event notdistinctly localized in the past varies inversely as the degree ofvividness of the mnemonic image, any conscious concentration of mind ona recollection will tend to bring it too near. In this way, then, anillusory propinquity may be given to a recalled event through a meredesire to dwell on it, or even a capricious wish to deceive one's self. When, for example, old friends come together and talk over the days ofyore, there is a gradual reinstatement of seemingly lost experiences, which often partakes of the character of a semi-voluntary process ofself-delusion. Through the cumulative effect of mutual reminder, incident after incident returns, adding something to the whole picturetill it acquires a degree of completeness, coherence, and vividness thatrender it hardly distinguishable from a very recent experience. Theprocess is like looking at a distant object through a field-glass. Mistiness disappears, fresh details come into view, till we seem toourselves to be almost within reach of the object. Where the mind habitually goes back to some painful circumstance underthe impulse of a morbid disposition to nurse regret, this momentaryillusion may become recurring, and amount to a partial confusion of thenear and the remote in our experience. An injury long brooded on seemsat length a thing that continually moves forward as we move; it alwayspresents itself to our memories as a very recent event. In states ofinsanity brought on by some great shock, we see this morbid tendency toresuscitate the dead past fully developed, and remote events andcircumstances becoming confused with present ones. On the other hand, in more healthy states of mind there presents itselfan exactly opposite tendency, namely, an impulse of the will to banishwhatever when recalled gives pain to the furthest conceivable regions ofthe past. Thus, when we have lost something we cherished dearly, and therecollection of it brings fruitless longing, we instinctively seek toexpel the recollection from our minds. The very feeling that what hasbeen can never again be, seems to induce this idea of a vast remotenessof the vanished reality. When, moreover, the lost object was fitted tocall forth the emotion of reverence, the impulse to magnify theremoteness of the loss may not improbably be reinforced by thecircumstance that everything belonging to the distant past is fitted onthat account to excite a feeling akin to reverence. So, again, anyrupture in our mental development may lead us to exaggerate the distanceof some past portion of our experience. When we have broken with ourformer selves, either in the way of worsening or bettering, we tend toproject these further into the past. It is only when the sting of the recollection is removed, when, forexample, the calling up of the image of a lost friend is no longeraccompanied with the bitterness of futile longing, that a healthy mindventures to nourish recollections of such remote events and to viewthese as part of its recent experiences. In this case the mnemonic imagebecomes transformed into a kind of present emotional possession, anelement of that idealized and sublimated portion of our experience withwhich all imaginative persons fill up the emptiness of their actuallives, and to which the poet is wont to give an objective embodiment inhis verse. _Distortions of Memory. _ It is now time to pass to the second group of illusions of memory, which, according to the analogy of visual errors, may be calledatmospheric illusions. Here the degree of error is greater than in thecase of illusions of time-perspective, since the very nature of theevents or circumstances is misconceived. We do not recall the event asit happened, but see it in part only, and obscured, or bent anddistorted as by a process of refraction. Indeed, this transformation ofthe past does closely correspond with the transformation of a visibleobject effected by intervening media. Our minds are such refractingmedia, and the past reappears to us not as it actually was when it wasclose to us, but in numerous ways altered and disguised by theintervening spaces of our conscious experience. To begin with, what we call recollection is uniformly a process ofsoftening the reality. When we appear to ourselves to realize events ofthe remote past, it is plain that our representation in a general wayfalls below the reality: the vividness, the intensity of our impressionsdisappears. More particularly, so far as our experiences are emotional, they tend thus to become toned down by the mere lapse of time and theimperfections of our reproductive power. That which we seem to see inthe act of recollection is thus very different from the reality. Not only is there this general deficiency in mnemonic representation, there are special deficiencies due to the fact of oblivescence. Ourmemories restore us only fragments of our past life. And just as objectsseen imperfectly at a great distance may assume a shape quite unliketheir real one, so an inadequate representation of a past event bymemory often amounts to misrepresentation. When revisiting a place thatwe have not seen for many years, we are apt to find that ourrecollection of it consisted only of some insignificant details, whicharranged themselves in our minds into something oddly unlike the actualscene. So, too, some accidental accompaniment of an incident in earlylife is preserved, as though it were the main feature, serving to givequite a false colouring to the whole occurrence. It seems quite impossible to account for these particular survivals, they appear to be so capricious. When a little time has elapsed after anevent, and the attendant circumstances fade away from memory, it isoften difficult to say why we were impressed with it as we afterwardsprove to have been. It is no doubt possible to see that many of therecollections of our childhood owe their vividness to the fact of theexceptional character of the events; but this cannot always berecognized. Some of them seem to our mature minds very oddly selected, although no doubt there are in every case good reasons, if we could onlydiscover them, why those particular incidents rather than any othersshould have been retained. The liability to error resulting from mere oblivescence and thearbitrary selection of mental images is seen most plainly, perhaps, inour subsequent representation and estimate of whole periods of earlylife. Our idea of any stage of our past history, as early childhood, orschool days, is built up out of a few fragmentary intellectual relicswhich cannot be certainly known to answer to the most important andpredominant experiences of the time. When, for example, we try to decidewhether our school days were our happiest days, as is so often alleged, it is obvious that we are liable to fall into illusion through theinadequacy of memory to preserve characteristic or typical features, andnone but these. We cannot easily recall the ordinary every-day level offeeling of a distant period of life, but rather think of exceptionalmoments of rejoicing or depression. The ordinary man's idea of theemotional experience of his school days is probably built up out of afew scrappy recollections of extraordinary and exciting events, such asunexpected holidays, success in the winning of prizes, famous "rows"with the masters, and so on. Besides the impossibility of getting at the average and prevailingmental tone of a distant section of life, there is a special difficultyin determining the degree of happiness of the past, arising from thefact that our memory for pleasures and for pains may not be equallygood. Most people, perhaps, can recall the enjoyments of the past muchmore vividly than the sufferings. On the other hand, there seem to besome who find the retention of the latter the easier of the two. Thisfact should not be forgotten in reading the narrative of early hardshipswhich some recent autobiographies have given us. Not only does our idea of the past become inexact by the mere decay anddisappearance of essential features, it becomes positively incorrectthrough the gradual incorporation of elements that do not properlybelong to it. Sometimes it is easy to see how these extraneous ideas getimported into our mental representation of a past event. Suppose, forexample, that a man has lost a valuable scarf-pin. His wife suggeststhat a particular servant, whose reputation does not stand too high, hasstolen it. When he afterwards recalls the loss, the chances are that hewill confuse the fact with the conjecture attached to it, and say heremembers that this particular servant did steal the pin. Thus, the pastactivity of imagination serves to corrupt and partially falsifyrecollections that have a genuine basis of fact. It is evident that this class of mnemonic illusions approximates incharacter to illusions of perception. When the imagination supplies theinterpretation at the very time, and the mind reads this into theperceived object, the error is one of perception. When the addition ismade afterwards, on reflecting upon the perception, the error is one ofmemory. The "fallacies of testimony" which depend on an adulteration ofpure observation with inference and conjecture, as, for example, theinaccurate and wild statements of people respecting their experiences atspiritualist _séances_, while they illustrate the curious blending ofboth kinds of error, are probably much oftener illusions of memory thanof perception. [125] Although in many cases we can account to ourselves for this confusion offact and imagination, in other cases it is difficult to see any closerelation between the fact remembered and the foreign element importedinto it. An idea of memory seems sometimes to lose its proper moorings, so to speak; to drift about helplessly among other ideas, and finally, by some chance, to hook itself on to one of these, as though itnaturally belonged to it. Anybody who has had an opportunity ofcarefully testing the truthfulness of his recollection of some remoteevent in early life will have found how oddly extraneous elements becomeincorporated into the memorial picture. Incidents get put into wrongplaces, the wrong persons are introduced into a scene, and so on. Hereagain we may illustrate the mnemonic illusion by a visual one. When atree standing before or behind a house and projecting above or to theside of it is not sharply distinguished from the latter, it may serve togive it a very odd appearance. These confusions of the mental image may arise even when only a shortinterval has elapsed. In the case of many of the fleeting impressionsthat are only half recollected, this kind of error is very easy. Thus, for example, I may have lent a book to a friend last week. I reallyremember the act of lending it, but have forgotten the person. But I amnot aware of this. The picture of memory has unknowingly to myself beenfilled up by this unconscious process of shifting and rearrangement, andthe idea of another person has by some odd accident got substituted forthat of the real borrower. If we could go deeply enough into the matter, we should, of course, be able to explain why this particular confusionarose. We might find, for example, that the two persons were associatedin my mind by a link of resemblance, or that I had dealings with theother person about the same time. Similarly, when we manage to join anevent to a wrong place, we may find that it is because we heard of theoccurrence when staying at the particular locality, or in some other wayhad the image of the place closely associated in our minds with theevent. But often we are wholly unable to explain the displacement. So far I have been speaking of the passive processes by which the pastcomes to wear a new face to our imaginations. In these our presenthabits of feeling and thinking take no part; all is the work of thepast, of the decay of memory, and the gradual confusion of images. Thisprocess of disorganization may be likened to the action of damp on someold manuscript, obliterating some parts, altering the appearance ofothers, and even dislocating certain portions. Besides this passiveprocess of transformation, there is a more active one in which ourpresent minds co-operate. In memory, as in perception and introspection, there is a process of preparation or preadjustment of mind, and herewill be found room for what I had called active error. This may beillustrated by the operation of "interpreting" an old manuscript whichhas got partially obliterated, or of "restoring" a faded picture; ineach of which operations error will be pretty sure to creep in throughan importation of the restorer's own ideas into the relic of the past. Just as when distant objects are seen mistily our imaginations come intoplay, leading us to fancy that we see something completely anddistinctly, so when the images of memory become dim, our presentimagination helps to restore them, putting a new patch into the oldgarment. If only there is some relic of the past event preserved, a baresuggestion of the way in which it may have happened will often sufficeto produce the conviction that it actually did happen in this way. Thesuggestions that naturally arise in our minds at such times will bearthe stamp of our present modes of experience and habits of thought. Hence, in trying to reconstruct the remote past, we are constantly indanger of importing our present selves into our past selves. The kind of illusion of memory which thus depends on the spontaneous orindependent activity of present imagination is strikingly illustrated inthe curious cases of mistaken identity with which the proceedings ofour law courts supply us from time to time. When a witness in goodfaith, but erroneously, affirms that a man is the same as an oldacquaintance of his, we may feel sure that there is some striking pointor points of similarity between the two persons. But this of itselfwould only partly account for the illusion, since we often see new facesthat, by a number of curious points of affinity, call up in atantalizing way old and familiar ones. What helps in this case toproduce the illusion is the preconception that the present man is thewitness's old friend. That is to say, his recollection is partly true, though largely false. He does really recall the similar feature, movement, or tone of voice; he only seems to himself to recall the restof his friend's appearance; for, to speak correctly, he projects thepresent impression into the past, and constructs his friend's face outof elements supplied by the new one. Owing to this cause, an illusion ofmemory is apt to multiply itself, one man's assertion of what happenedproducing by contagion a counterfeit of memory's record in other minds. I said just now that we tend to project our present modes of experienceinto the past. We paint our past in the hues of the present. Thus weimagine that things which impressed us in some remote period of lifemust answer to what is impressive in our present stage of mentaldevelopment. For example, a person recalls a hill near the home of hischildhood, and has the conviction that it was of great height. Onrevisiting the place he finds that the eminence is quite insignificant. How can we account for this? For one thing, it is to be observed that tohis undeveloped childish muscles the climbing to the top meant aconsiderable expenditure of energy, to be followed by a sense offatigue. The man remembers these feelings, and "unconsciously reasoning"by present experience, that is to say, by the amount of walking whichwould now produce this sense of fatigue, imagines that the height wasvastly greater than it really was. Another reason is, of course, that awider knowledge of mountains has resulted in a great alteration of theman's standard of height. From this cause arises a tendency generally to exaggerate theimpressions of early life. Youth is the period of novel effects, whenall the world is fresh, and new and striking impressions crowd inthickly on the mind. Consequently, it takes much less to produce a givenamount of mental excitation in childhood than in after-life. In lookingback on this part of our history, we recall for the most part just thoseevents and scenes which deeply stirred our minds by their strangeness, novelty, etc. , and so impressed themselves on the tablet of our memory;and it is this sense of something out of the ordinary beat that givesthe characteristic colour to our recollection. In other words, weremember something as wonderful, admirable, exceptionally delightful, and so on, rather than as a definitely imagined event. This being so, weunconsciously transform the past occurrence by reasoning from ourpresent standard of what is impressive. Who has not felt an unpleasantdisenchantment on revisiting some church, house, or park that seemed awondrous paradise to his young eyes? All our feelings are capable ofleading us into this kind of illusion. What seemed beautiful or awfulto us as children, is now pictured in imagination as corresponding towhat moves our mature minds to delight or awe. One cannot help wonderingwhat we should think of our early heroes or heroines if we could seethem again with our adult eyes exactly as they were. While the past may thus take on an illusory hue through the veryprogress of our experience and our emotional life, it may become furthertransformed by a more conscious process, namely, the idealizing touch ofa present feeling. The way in which the emotions of love, reverence, andso on, thus transform their lost objects is too well known to needillustration. Speaking generally, we may say that in healthy minds theplay of these impulses of feeling results in a softening of the harsherfeatures of the past, and in an idealization of its happier and brighteraspects. As Wordsworth says, we may assign to Memory a pencil-- "That, softening objects, sometimes even Outstrips the heart's demand; "That smoothes foregone distress, the lines Of lingering care subdues, Long-vanished happiness refines, And clothes in brighter hues. "[126] Enough has now been said, perhaps, to show in how many ways ourretrospective imagination transforms the actual events of our past life. So thoroughly, indeed, do the relics of this past get shaken together innew kaleidoscopic combinations, so much of the result of laterexperiences gets imported into our early years, that it may well beasked whether, if the record of our actual life were ever read out tous, we should be able to recognize it. It looks as though we could besure of recalling only recent events with any degree of accuracy andcompleteness. As soon as they recede at any considerable distance fromus, they are subject to a sort of atmospheric effect. Much growsindistinct and drops altogether out of sight, and what is still seenoften takes a new and grotesquely unlike shape. More than this, the playof fancy, like the action of some refracting medium, bends and distortsthe outlines of memory's objects, making them wholly unlike theoriginals. _Hallucinations of Memory. _ We will now go on to the third class of mnemonic error, which I havecalled the spectra of memory, where there is not simply a transformationof the past event, but a complete imaginative creation of it. This classof error corresponds, as I have observed, to an hallucination in theregion of sense-perception. And just as we distinguished between thosehallucinations of sense which arise first of all through someperipherally caused subjective sensation, and those which want even thiselement of reality and depend altogether on the activity of imagination, so we may mark off two classes of mnemonic hallucination. The falserecollection may correspond to something past--and to this extent be arecollection--though not to any objective fact, but only to a subjectiverepresentation of such a fact, as, for example, a dream. In this casethe imitation of the mnemonic process may be very definite and complete. Or the false recollection may be wholly a retrojection of a presentmental image, and so by no stretch of language be deserving of the namerecollection. It is doubtful whether by any effort of will a person could bringhimself to regard a figment of his present imagination as representativeof a past reality. Definite and complete hallucinations of this sort donot in normal circumstances arise. It seems necessary for a completeillusion of memory that there should be something past and recovered atthe moment, though this may not be a real personal experience. [127] Onthe other hand, it is possible, as we shall presently see, under certaincircumstances, to create out of present materials, and in a vague andindefinite shape, pure phantoms of past experience, that is to say, quasi-mnemonic images to which there correspond no past occurrenceswhatever. All recollection, as we have seen, takes place by means of a presentmental image which returns with a certain degree of vividness, and isinstantaneously identified with some past event. In many cases thisinstinctive process of identification proves to be legitimate, for, as amatter of fact, real impressions are the first and the commonest sourceof such lively mnemonic images. But it is not always so. There are othersources of our mental imagery which compete, so to speak, with theregion of real personal experience. And sometimes these leave behindthem a vivid image having all the appearance of a genuine mnemonicimage. When this is so, it is impossible by a mere introspective glanceto detect the falsity of the message from the past. We are in the sameposition as the purchaser in a jet market, where a spurious commodityhas got inextricably mixed up with the genuine, and there is no readycriterion by which he can distinguish the true from the false. Such aperson, if he purchases freely, is pretty sure to make a number ofmistakes. Similarly, all of us are liable to take counterfeit mnemonicimages for genuine ones; that is to say, to fall into an illusion of"recollecting" what never really took place. But what, it may be asked, are these false and illegitimate sources ofmnemonic images, these unauthorized mints which issue a spurious mentalcoinage, and so confuse the genuine currency? They consist of tworegions of our internal mental life, which most closely resemble theactual perception of real things in vividness and force, namely, dream-consciousness and waking imagination. Each of these may introduceinto the mind vivid images which afterwards tend, under certaincircumstances, to assume the guise of recollections of actual events. That our dream-experience may now and again lead us into illusoryrecollection has already been hinted. And it is easy to understand whythis is so. When dreaming we have, as we have seen, a mental experiencewhich closely approximates in intensity and reality to that of wakingperception. Consequently, dreams may leave behind them, for a time, vivid images which simulate the appearance of real images of memory. Most of us, perhaps, have felt this after-effect of dreaming on ourwaking thoughts. It is sometimes very hard to shake off the impressionleft by a vivid dream, as, for example, that a dead friend has returnedto life. During the day that follows the dream, we have at intermittentmoments something like an assurance that we have seen our lost friend;and though we immediately correct the impression by reflecting that weare recalling but a dream, it tends to revive within us with a strangepertinacity. In addition to this proximate effect of a dream in disturbing the normalprocess of recollection, there is reason to suppose that dreams mayexert a more remote effect on our memories. So widely different in itsform is our dreaming from our waking experience, that our dreams arerarely recalled as wholes with perfect distinctness. They revive in usonly as disjointed fragments, and only for brief moments when someaccidental resemblance in the present happens to stir the latent tracethey have left on our minds. We get sudden flashes out of ourdream-world, and the process is too rapid, too incomplete for us toidentify the region whence the flashes come. It is highly probable that our dreams are, to a large extent, answerablefor the sense of familiarity that we sometimes experience in visiting anew locality or in seeing a new face. If, as we have found some of thebest authorities saying, we are, when asleep, always dreaming more orless distinctly, and if, as we know, dreaming is a continual process oftransformation of our waking impressions in new combinations, it is notsurprising that our dreams should sometimes take the form of forecastsof our waking life, and that consequently objects and scenes of thislife never before seen should now and again wear a familiar look. That some instances of this puzzling sense of familiarity can beexplained in this way is proved. Thus, Paul Radestock, in the work_Schlaf und Traum_, already quoted, tells us: "When I have been taking awalk, with my thoughts quite unfettered, the idea has often occurred tome that I had seen, heard, or thought of this or that thing once before, without being able to recall when, where, and in what circumstances. This happened at the time when, with a view to the publication of thepresent work, I was in the habit of keeping an exact record of mydreams. Consequently, I was able to turn to this after theseimpressions, and on doing so I generally found the conjecture confirmedthat I had previously dreamt something like it. " Scientific inquiry isoften said to destroy all beautiful thoughts about nature and life; butwhile it destroys it creates. Is it not almost a romantic idea that justas our waking life images itself in our dreams, so our dream-life maysend back some of its shadowy phantoms into our prosaic every-day world, touching this with something of its own weird beauty? Not only may dreams beget these momentary illusions of memory, they maygive rise to something like permanent illusions. If a dream serves toconnect a certain idea with a place or person, and subsequent experiencedoes not tend to correct this, we may keep the belief that we haveactually witnessed the event. And we may naturally expect that thisresult will occur most frequently in the case of those who habituallydream vividly, as young children. It seems to me that many of the quaint fancies which children get intotheir heads about things they hear of arise in this way. I know a personwho, when a child, got the notion that when his baby-brother was weaned, he was taken up on a grassy hill and tossed about. He had a vivid ideaof having seen this curious ceremony. He has in vain tried to get anexplanation of this picturesque rendering of an incident of babyhoodfrom his friends, and has come to the conclusion that it was the resultof a dream. If, as seems probable, children's dreams thus give rise tosubsequent illusions of memory, the fact would throw a curious light onsome of the startling quasi-records of childish experience to be metwith in autobiographical literature. Odd though it may at first appear, old age is said to resemble youth inthis confusion of dream-recollection with the memory of wakingexperience. Dr. Carpenter[128] tells us of "a lady of advanced agewho . .. Continually dreams about passing events, and seems entirely unableto distinguish between her dreaming and her waking experiences, narrating the former with implicit belief in them, and giving directionsbased on them. " This confusion in the case of the old may possiblyarise not from an increase in the intensity of the dreams, but from adecrease in the intensity of the waking impressions. As Sir HenryHolland remarks, [129] in old age life approaches to the state of adream. The other source of what may, by analogy with the hallucinations ofsense, be called the peripherally originating spectra of memory iswaking imagination. In certain morbid conditions of mind, and in thecase of the few healthy minds endowed with special imaginative force, the products of this mental activity, may, as we saw when dealing withillusions of perception, closely resemble dreams in their vividness andapparent actuality. When this is the case, illusions of memory may ariseat once just as in the case of dreams. This will happen more easily whenthe imagination has for some time been occupied with the same group ofideal scenes, persons, or events. To Dickens, as is well known, hisfictitious characters were for the time realities, and after he hadfinished his story their forms and their doings lingered with him, assuming the aspect of personal recollections. So, too, the energeticactivity of imagination which accompanies a deep and absorbing sympathywith another's painful experiences, may easily result in so vivid arealization of all their details as to leave an after-sense of_personal_ suffering. All highly sympathetic persons who have closelyaccompanied beloved friends through a great sorrow have known somethingof this subsequent feeling. The close connection and continuity between normal and abnormal statesof mind is illustrated in the fact that in insanity the illusion oftaking past imaginations for past realities becomes far more powerfuland persistent. Abercrombie (_Intellectual Powers_, Part III. Sec. Iv. §2, "Insanity") speaks of "visions of the imagination which have formerlybeen indulged in of that kind which we call waking dreams orcastle-building recurring to the mind in this condition, and nowbelieved to have a real existence. " Thus, for example, one patientbelieved in the reality of the good luck previously predicted by afortune-teller. Other writers on mental disease observe that it is acommon thing for the monomaniac to cherish the delusion that he hasactually gained the object of some previous ambition, or is undergoingsome previously dreaded calamity. Nor is it necessary to these illusions of memory that there should beany exceptional force of imagination. A fairly vivid representation toourselves of anything, whether real or fictitious, communicated byothers, will often result in something very like a personalrecollection. In the case of works of history and fiction, which adoptthe narrative tense, this tendency to a subsequent illusion of memory isstrengthened by the disposition of the mind at the moment of reading toproject itself backwards as in an act of recollection. This is a pointwhich will be further dealt with in the next chapter. In most cases, however, illusions of memory growing out of previousactivities of the imagination appear only after the lapse of some time, when in the natural course of things the mental images derived fromactual experience would sink to a certain degree of faintness. Habitualnovel-readers often catch themselves mistaking the echo of some passagein a good story for the trace left by an actual event. A person's name, a striking saying, and even an event itself, when we first come acrossit or experience it, may for a moment seem familiar to us, and to recallsome past like impression, if it only happens to resemble something inthe works of a favourite novelist. And so, too, any recital of another'sexperience, whether oral or literary, if it deeply interests us andawakens a specially vivid imagination of the events described, mayeasily become the starting-point of an illusory recollection. Children are in the habit of "drinking in" with their vigorous and eagerimaginations what is told them and read to them, and hence they arespecially likely to fall into this kind of error. Not only so: when theygrow up and their early recollections lose their definiteness, becominga few fragments saved from a lost past, it must pretty certainly happenthat if any ideas derived from these recitals are preserved, they willsimulate the form of memories. Thus, I have often caught myself for amoment under the sway of the illusion that I actually visited theExhibition of 1851, the reason being that I am able to recall thedescriptions given to me of it by my friends, and the excitementattending their journey to London on the occasion. It is to be addedthat repetition of the act of imagination will tend still further todeepen the subsequent feeling that we are recollecting something. AsHartley well observes, a man, by repeating a story, easily comes tosuppose that he remembers it. [130] Here, then, we have another source of error that we must take intoaccount in judging of the authenticity of an autobiographical narrationof the events of childhood. The more imaginative the writer, the greaterthe risk of illusion from this source as well as from that ofdream-fancies. It is highly probable, indeed, that in such full andexplicit records of very early life as those given by Rousseau, byGoethe, or by De Quincey, some part of the quasi-narrative is based onmental images which come floating down the stream of time, not from thesubstantial world of the writer's personal experience, but from the airyregion of dream-land or of waking fancy. It is to be added that even when the quasi-recollection does answer to areal event of childish history, it may still be an illusion. The factthat others, in narrating events to us, are able to awaken imaginationsthat afterwards appear as past realities, suggests that much of oursupposed early recollection owes its existence to what our parents andfriends have from time to time told us respecting the first stages ofour history. [131] We see, then, how much uncertainty attaches to allautobiographical description of very early life. Modern science suggests another possible source of these distinctspectra of memory. May it not happen that, by the law of hereditarytransmission, which is now being applied to mental as well as bodilyphenomena, ancestral experiences will now and then reflect themselvesin our mental life, and so give rise to apparently personalrecollections? No one can say that this is not so. When the infant firststeadies his eyes on a human face, it may, for aught we know, experiencea feeling akin to that described above, when through a survival ofdream-fancy we take some new scene to be already familiar. At the agewhen new emotions rapidly develop themselves, when our hearts are fullof wild romantic aspirations, do there not seem to blend with the eagerpassion of the time deep resonances of a vast and mysterious past, andmay not this feeling be a sort of reminiscence of prenatal, that is, ancestral experience? This idea is certainly a fascinating one, worthy to be a new scientificsupport for the beautiful thought of Plato and of Wordsworth. But in ourpresent state of knowledge, any reasoning on this supposition wouldprobably appear too fanciful. Some day we may find out how muchancestral experience is capable of bequeathing in this way, whethersimply shadowy, undefinable mental tendencies, or something likedefinite concrete ideas. If, for example, it were found that a childthat was descended from a line of seafaring ancestors, and that hadnever itself seen or heard of the "dark-gleaming sea, " manifested afeeling of recognition when first beholding it, we might be pretty surethat such a thing as recollection of prenatal events does take place. But till we have such facts, it seems better to refer the "shadowyrecollections" to sources which fall within the individual's ownexperience. We may now pass to those hallucinations of memory which are analogous tothe _centrally_ excited hallucinations of sense-perception. As I haveobserved, these are necessarily vague and imperfectly developed. I have already had occasion to touch on the fact of the vast amount ofour forgotten experience. And I observed that forgetfulness was a commonnegative condition of mnemonic illusion. I have now to complete thisstatement by the observation that total forgetfulness of any period orstage of our past experience necessarily tends to a vague kind ofhallucination. In looking back on the past, we see no absolute gaps inthe continuity of our conscious life; our image of this past isessentially one of an unbroken series of conscious experiences. But ifthrough forgetfulness a part of the series is effaced from memory, how, it may be asked, is it possible to construct this perfectly continuousline? The answer is that we fill up such lacunæ vaguely by help of somevery imperfectly imagined common type of conscious experience. Just asthe eye sees no gap in its field of vision corresponding to the "blindspot" of the retina, but carries its impression over this area, somemory sees no lacuna in the past, but carries its image of consciouslife over each of the forgotten spaces. Sometimes this process of filling in gaps in the past becomes morecomplete. Thus, for example, in recalling a particular night a week orso ago, I instinctively represent it to myself as so many hours of lyingin bed with the waking sensations appropriate to the circumstances, asthose of bodily warmth and rest, and of the surrounding silence anddarkness. It is apparent that I cannot conceive myself apart from some mode ofconscious experience. In thinking of myself in any part of the past orfuture in which there is actually no consciousness, or of which theconscious content is quite unknown to me, I necessarily imagine myselfas consciously experiencing something. If I picture myself under anydefinitely conceived circumstances, I irresistibly import into my mentalimage the feelings appropriate to these surroundings. In this way, people tend to imagine themselves after death as lying in the grave, feeling its darkness and its chilliness. If the circumstances of thetime are not distinctly represented, the conception of the consciousexperience which constitutes that piece of the ego is necessarily vague, and seems generally to resolve itself into a representation of ourselvesas dimly _self-conscious_. What this consciousness of self consists ofis a point that will be taken up presently. _Illusions with respect to Personal Identity. _ It would seem to follow from these errors in imaginatively filling upour past life, that our consciousness of personal identity is by nomeans the simple and exact process which it is commonly supposed to be. I have already remarked that the very fact of there being so large aregion of the irrevocable in our past experience proves ourconsciousness of personal continuity to be largely a matter ofinference, or of imaginative conjecture, and not simply of immediaterecollection. Indeed, it may be said that our power of ignoring wholeregions of the past and of leaping complacently over huge gaps in ourmemory and linking on conscious experience with conscious experience, involves an illusory sense of continuity, and so far of personalidentity. Thus, our ordinary image of our past life, if only by omittingthe very large fraction passed in sleep, in at least an approximatelyunconscious state, clearly contains an ingredient of illusion. [132] It is to be added that the numerous falsifications of our past history, which our retrospective imagination is capable of perpetrating, make ourrepresentation of ourselves at different moments and in different stagesof our past history to a considerable extent illusory. Thus, though tomistake a past dream-experience for a waking one may not be to lose orconfuse the sense of identity, since our dreams are, after all, a partof our experience, yet to imagine that we have ourselves seen what wehave only heard from another or read is clearly to confuse theboundaries of our identity. And with respect to longer sections of ourhistory, it is plain that when we wrongly assimilate our remote to ourpresent self, and clothe our childish nature with the feelings and theideas of our adult life, we identify ourselves overmuch. In this way, through the corruption of our memory, a kind of sham self gets mixed upwith the real self, so that we cannot, strictly speaking, be sure thatwhen we project a mnemonic image into the remote past we are not reallyrunning away from our true personality. So far I have been touching only on slight errors in the recognition ofthat identical self which is represented as persisting through all thefluctuations of conscious life. Other and grosser illusions connectedwith personal identity are also found to be closely related to defectsor disturbances of the ordinary mnemonic process, and so can be besttreated here. In order to understand these, we must inquire a littleinto the nature of our idea and consciousness of a persistent self. Here, again, I would remind the reader that I am treating the point onlyso far as it can be treated scientifically or empirically, that is tosay, by examining what concrete facts or data of experience are taken upinto the idea of self. I do not wish to foreclose the philosophicquestion whether anything more than this empirical content is involvedin the conception. My idea of myself as persisting appears to be built up of certainsimilarities in the succession of my experiences. Thus, my permanentself consists, on the bodily side, of a continually renewable perceptionof my own organism, which perception is mainly visual and tactual, andwhich remains pretty constant within certain limits of time. With thisobjective similarity is closely conjoined a subjective similarity. Thus, the same sensibilities continue to characterize the various parts of myorganism. Similarly, there are the higher intellectual, emotional, andmoral peculiarities and dispositions. My idea of my persistent self isessentially a collective image representing a relatively unchangingmaterial object, endowed with unchanging sensibilities and forming akind of support for permanent higher mental attributes. The construction of this idea of an enduring unchanging ego is renderedvery much easier by the fact that certain concrete feelings areapproximately constant elements in our mental life. Among these must beranked first that dimly discriminated mass of organic sensation which inaverage states of health is fairly constant, and which stands in sharpcontrast to the fluctuating external sensations. These feelings enterinto and profoundly colour each person's mental image of himself. Inaddition to this, there are the frequently recurring higher feelings, the dominant passions and ideas which approximate more or less closelyto constant factors of our conscious experience. This total image of the ego becomes defined and rendered precise by anumber of distinctions, as that between my own body or that particularmaterial object with which are intimately united all my feelings, andother material objects in general; then between my organism and otherhuman organisms, with which I learn to connect certain feelingsanswering to my own, but only faintly represented instead of actuallyrealized feelings. To these prime distinctions are added others, hardlyless fundamental, as those between my individual bodily appearance andthat of other living bodies, between my personal and characteristicmodes of feeling and thinking and those of others, and so on. Our sense of personal identity may be said to be rooted in that specialside of the mnemonic process which consists in the linking of allsequent events together by means of a thread of common consciousness. Itis closely connected with that smooth, gliding movement of imaginationwhich appears to involve some more or less distinct consciousness of theuniting thread of similarity. And so long as this movement is possible, so long, that is to say, as retrospective imagination detects the commonelement, which we may specifically call the recurring consciousness ofself, so long is there the undisturbed assurance of personal identity. Nay, more, even when such a recognition might seem to be difficult, ifnot impossible, as in linking together the very unlike selves, viewedboth on their objective and subjective sides, of childhood, youth, andmature life, the mind manages, as we have seen, to feign to itself asufficient amount of such similarity. But this process of linking stage to stage, of discerning the common orthe recurring amid the changing and the evanescent, has its limits. Every great and sudden change in our experience tends, momentarily atleast, to hinder the smooth reflux of imagination. It makes too sharp abreak in our conscious life, so that imagination is incapable ofspanning the gap and realizing the then and the now as parts of aconnected continuous tissue. [133] These changes may be either objective or subjective. Any suddenalteration of our bodily appearance sensibly impedes the movement ofimagination. A patient after a fever, when he first looks in the glass, exclaims, "I don't know myself. " More commonly the bodily changes whichaffect the consciousness of an enduring self are such as involveconsiderable alterations of coenæsthesis, or the mass of stableorganic sensation. Thus, the loss of a limb, by cutting off a portion ofthe old sensations through which the organism may be said to beimmediately felt, and by introducing new and unfamiliar feelings, willdistinctly give a shock to our consciousness of self. Purely subjective changes, too, or, to speak correctly, such as areknown subjectively only, will suffice to disturb the sense of personalunity. Any great moral shock, involving something like a revolution inour recurring emotional experience, seems at the moment to rupture thebond of identity. And even some time after, as I have already remarked, such cataclysms in our mental geology lead to the imaginative thrustingof the old personality away from the new one under the form of a "deadself. "[134] We see, then, that the failure of our ordinary assurance of personalidentity is due to the recognition of difference without similarity. Itarises from an act of memory--for the mind must still be able to recallthe past, dimly at least--but from a memory which misses its habitualsupport in a recognized element of constancy. If there is no memory, that is to say, if the past is a complete blank, the mind simply feels arupture of identity without any transformation of self. This is ourcondition on awaking from a perfectly forgotten period of sleep, or froma perfectly unconscious state (if such is possible) when induced byanæsthetics. Such gaps are, as we have seen, easily filled up, and thesense of identity restored by a kind of retrospective "skipping. " On theother hand, the confusion which arises from too great and violent atransformation of our _remembered_ experiences is much less easilycorrected. As long as the recollection of the old feelings remains, andwith this the sense of violent contrast between the old and the newones, so long will the illusion of two sundered selves tend to recur. The full development of this process of imaginative fission or cleavageof self is to be met with in mental disease. The beginnings of suchdisease, accompanied as they commonly are with disturbances of bodilysensations and the recurring emotions, illustrate in a very interestingway the dependence of the recognition of self on a certain degree ofuniformity in the contents of consciousness. The patient, when firstaware of these changes, is perplexed, and often regards the new feelingsas making up another self, a foreign _Tu_, as distinguished from thefamiliar _Ego_. And sometimes he expresses the relation between the oldand the new self in fantastic ways, as when he imagines the former to beunder the power of some foreign personality. When the change is complete, the patient is apt to think of his formerself as detached from his present, and of his previous life as a kind ofunreal dream; and this fading away of the past into shadowy unreal formshas, as its result, a curious aberration in the sense of time. Thus, itis said that a patient, after being in an asylum only one day, willdeclare that he has been there a year, five years, and even tenyears. [135] This confusion as to self naturally becomes thestarting-point of illusions of perception; the transformation of selfseeming to require as its logical correlative (for there is a crudelogic even in mental disease) a transformation of the environment. Whenthe disease is fully developed under the particular form of monomania, the recollection of the former normal self commonly disappearsaltogether, or fades away into a dim image of some perfectly separatepersonality. A new ego is now fully substituted for the old. In otherand more violent forms of disease (dementia) the power of connecting thepast and present may disappear altogether, and nothing but the _disjectamembra_ of an ego remain. * * * * * Enough has, perhaps, been said to show how much of uncertainty and ofself-deception enters into the processes of memory. This much-esteemedfaculty, valuable and indispensable though it certainly is, can clearlylay no claim to that absolute infallibility which is sometimes said tobelong to it. Our individual recollection, left to itself, is liable toa number of illusions even with regard to fairly recent events, and inthe case of remote ones it may be said to err habitually and uniformlyin a greater or less degree. To speak plainly, we can never be certainon the ground of our personal recollection alone that a distant eventhappened exactly in the way and at the time that we suppose. Nor doesthere seem to be any simple way by mere reflection on the contents ofour memory of distinguishing what kinds of recollection are likely to beillusory. How, then, it may be asked, can we ever be certain that we arefaithfully recalling the actual events of the past? Given a fairly good, that is, a cultivated memory, it may be said that in the case of veryrecent events a man may feel certain that, when the conditions ofcareful attention at the time to what really happened were present, adistinct recollection is substantially correct. Also it is obvious thatwith respect to all repeated experiences our memories afford practicallysafe guides. When memory becomes the basis of some item of generalizedknowledge, as, for example, of the truth that the pain of indigestionhas followed a too copious indulgence in rich food, there is little roomfor an error of memory properly so called. On the other hand, when anevent is not repeated in our experience, but forms a unique link in ourpersonal history, the chances of error increase with the distance of theevent; and here the best of us will do well to have resort to a processof verification or, if necessary, of correction. In order thus to verify the utterances of memory, we must look beyondour own internal mental states to some external facts. Thus, therecollections of our early life may often be tested by letters writtenby ourselves or our friends at the time, by diaries, and so on. Whenthere is no unerring objective record to be found, we may have recourseto the less satisfactory method of comparing our recollections withthose of others. By so doing we may reach a rough average recollectionwhich shall at least be free from any individual error corresponding tothat of personal equation in perception. But even thus we cannot be sureof eliminating all error, since there may be a cause of illusion actingon all our minds alike, as, for example, the extraordinary nature of theoccurrence, which would pretty certainly lead to a common exaggerationof its magnitude, etc. , and since, moreover, this process of comparingrecollections affords an opportunity for that reading back a presentpreconception into the past to which reference has already been made. The result of our inquiry is less alarming than it looks at first sight. Knowledge is valuable for action, and error is chiefly hurtful in so faras it misdirects conduct. Now, in a general way, we do not need to actupon a recollection of single remote events; our conduct is sufficientlyshaped by an accurate recollection of single recent events, togetherwith those bundles of recollections of recurring events and sequences ofevents which constitute our knowledge of ourselves and our commonknowledge of the world about us. Nature has done commendably well inendowing us with the means of cultivating our memories up to this point, and we ought not to blame her for not giving us powers which would onlyvery rarely prove of any appreciable practical service to us. NOTE. MOMENTARY ILLUSIONS OF SELF-CONSCIOUSNESS. The account of the apparent ruptures in our personal identity given inthis chapter may help us to understand the strange tendency to confuseself with other objects which occasionally appears in wakingconsciousness and in dreams. These errors may be said generally to bedue to the breaking up of the composite image of self into itsfragments, and the regarding of certain of these only. Thus, themomentary occurrence of partial illusion in intense sympathy withothers, including that imaginative projection of self into inanimateobjects, to which reference has already been made, may be said to dependon exclusive attention to the subjective aspect of self, to the totaldisregard of the objective aspect. In other words, when we thusmomentarily "lose ourselves, " or merge our own existence in that ofanother object, we clearly let drop out of sight the visualrepresentation of our own individual organism. On the other hand, whenin dreams we double our personality, or represent to ourselves anexternal self which becomes the object of visual perception, it isprobably because we isolate in imagination the objective aspect of ourpersonality from the other and subjective aspect. It is not at allunlikely that the several confusions of self touched on in this chapterhave had something to do with the genesis of the various historicaltheories of a transformed existence, as, for example, the celebrateddoctrine of metempsychosis. CHAPTER XI. ILLUSIONS OF BELIEF. Our knowledge is commonly said to consist of two largevarieties--Presentative and Representative. Representative knowledge, again, falls into two chief divisions. The first of these is Memory, which, though not primary or original, like presentative knowledge, isstill regarded as directly or intuitively certain. The second divisionconsists of all other representative knowledge besides memory, including, among other varieties, our anticipations of the future, ourknowledge of others' past experience, and our general knowledge aboutthings. There is no one term which exactly hits off this large sphere ofcognition: I propose to call it Belief. I am aware that this is by nomeans a perfect word for my purpose, since, on the one hand, it suggeststhat every form of this knowledge must be less certain than presentativeor mnemonic knowledge, which cannot be assumed; and since, on the otherhand, the word is so useful a one in psychology, for the purpose ofmarking off the subjective fact of assurance in all kinds of cognition. Nevertheless, I know not what better one I could select in order tomake my classification answer as closely as a scientific treatment willallow to the deeply fixed distinctions of popular psychology. It might at first seem as if perception, introspection, and memory mustexhaust all that is meant by immediate, or self-evident, knowledge, andas if what I have here called belief must be uniformly mediate, derivate, or inferred knowledge. The apprehension of something nowpresent to the mind, externally or internally, and the reapprehensionthrough the process of memory of what was once so apprehended, mightappear to be the whole of what can by any stretch of language be calleddirect cognition of things. This at least would seem to follow from theempirical theory of knowledge, which regards perception and memory asthe ground or logical source of all other forms of knowledge. And even if we suppose, with some philosophers, that there are certaininnate principles of knowledge, it seems now to be generally allowedthat these, apart from the particular facts of experience, are merelyabstractions; and that they only develop into complete knowledge whenthey receive some empirical content, which must be supplied either bypresent perception or by memory. So that in this case, too, all definiteconcrete knowledge would seem to be either presentative cognition, memory, or, lastly, some mode of inference from these. A little inquiry into the mental operations which I here include underthe name belief will show, however, that they are by no means uniformlyprocess of inference. To take the simplest form of such knowledge, anticipation of some personal experience: this may arise quite apartfrom recollection, as a spontaneous projection of a mental image intothe future. A person may feel "intuitively certain" that something isgoing to happen to him which does not resemble anything in his pastexperience. Not only so; even when the expectation corresponds to a bitof past experience, this source of the expectation may, under certaincircumstances, be altogether lost to view, and the belief assume asecondarily automatic or intuitive character. Thus, a man may have firstentertained a belief in the success of some undertaking as the result ofa rough process of inference, but afterwards go on trusting when thegrounds for his confidence are wholly lost sight of. This much may suffice for the present to show that belief sometimesapproximates to immediate, or self-evident, conviction. How far this isthe case will come out in the course of our inquiry into its differentforms. This being so, it will be needful to include in our present studythe errors connected with the process of belief in so far as theysimulate the immediate instantaneous form of illusion. What I have here called belief may be roughly distinguished into simpleand compound belief. By a simple belief I mean one which has to do witha single event or fact. It includes simple modes of expectation, as wellas beliefs in single past facts not guaranteed by memory. A compoundbelief, on the other hand, has reference to a number of events or facts. Thus, our belief in the continued existence of a particular object, aswell as our convictions respecting groups or classes of events, must beregarded as compound, since they can be shown to include a number ofsimple beliefs. A. _Simple Illusory Belief: Expectation. _ It will be well to begin our inquiry by examining the errors connectedwith simple expectations, so far as these come under our definition ofillusion. And here, following our usual practice, we may set out with avery brief account of the nature of the intellectual process in itscorrect form. For this purpose we shall do well to take a complete ordefinite anticipation of an event as our type. [136] The ability of the mind to move forward, forecasting an order of eventsin time, is clearly very similar to its power of recalling events. Eachdepends on the capability of imagination to represent a sequence ofevents or experiences. The difference between the two processes is thatin anticipation the imagination setting out from the present traces thesuccession of experiences in their actual order, and not in the reverseorder. It would thus appear to be a more natural and easy process thanrecollection, and observation bears out this conclusion. Any objectpresent to perception which is associated with antecedents andconsequents with the same degree of cohesion, calls up its consequentsrather than its antecedents. The spectacle of the rising of the suncarries the mind much more forcibly forwards to the advancing morningthan backwards to the receding night. And there is good reason tosuppose that in the order of mental development the power of distinctlyexpecting an event precedes that of distinctly recollecting one. Thus, in the case of the infant mind, as of the animal intelligence, thepresence of signs of coming events, as the preparation of food, seems toexcite distinct and vivid expectation. [137] As a mode of assurance, expectation is clearly marked off from memory, and is not explainable by means of this. It is a fundamentally distinctkind of conviction. So far as we are capable of analyzing it, we may saythat its peculiarity is its essentially active character. To expect athing is to have stirred the active impulses, including the powers ofattention; it is to be on the alert for it, to have the attentionalready focussed for it, and to begin to rehearse the actions which theactual happening of the event--for example, the approach of a welcomeobject--would excite. It thus stands in marked contrast to memory, whichis a passive attitude of mind, becoming active only when it gives riseto the expectation of a recurrence of the event. [138] And now let us pass to the question whether expectation ever takes theform of immediate knowledge. It may, perhaps, be objected that theanticipation of something future cannot be knowledge at all in the sensein which the perception of something present or the recollection ofsomething past is knowledge. But this objection, when examined closely, appears to be frivolous. Because the future fact has not yet come intothe sphere of actual existence, it is none the less the object of aperfect assurance. [139] But, even if it is conceded that expectation is knowledge, the objectionmay still be urged that it cannot be immediate, since it is the verynature of expectation to ground itself on memory. I have already hintedthat this is not the case, and I shall now try to show that what iscalled expectation covers much that is indistinguishable from immediateintuitive certainty, and consequently offers room for an illusory formof error. Let us set out with the simplest kind of expectation, the anticipationof something about to happen within the region of our personalexperience, and similar to what has happened before. And let the comingof the event be first of all suggested by some present external fact orsign. Suppose, for example, that the sky is heavy, the air sultry, andthat I have a bad headache; I confidently anticipate a thunderstorm. Itwould commonly be said that such an expectation is a kind of inferencefrom the past. I remember that these appearances have been followed by athunderstorm very often, and I infer that they will in this new case beso followed. To this, however, it may be replied that in most cases there is noconscious going back to the past at all. As I have already remarked, anticipation is pretty certainly in advance of memory in early life. Andeven after the habit of passing from the past to the future, from memoryto expectation, has been formed, the number of the past repetitions ofexperience would prevent the mind's clearly reverting to them. And, further, the very force of habit would tend to make the transition frommemory to expectation more and more rapid, automatic, and unconscious. Thus it comes about that all distinctly suggested approaching eventsseem to be expected by a kind of immediate act of belief. The presentsigns call up the representation of the coming event with all the forceof a direct intuition. At least, it may be said that if a process ofinference, it is one which has the minimum degree of consciousness. It might still be urged that the mind passes from the _present_ facts assigns, and so still performs a kind of reasoning process. This is, nodoubt, true, and differentiates expectation from perception, in whichthere is no conscious transition from the presented to the represented. Still I take it that this is only a process of reasoning in so far asthe sign is consciously generalized, and this is certainly not true ofearly expectations, or even of any expectations in a wholly uncultivatedmind. For these reasons I think that any errors involved in such ananticipation may, without much forcing, be brought under our definitionof illusion. When due altogether to the immediate force of suggestion ina present object or event, and not involving any conscious transitionfrom past to future, or from general truth to particular instance, theseerrors appear to me to have more of the character of illusions than ofthat of fallacies. Much the same thing may be said about the vivid anticipations of afamiliar kind of experience called up by a clear and consecutive verbalsuggestion. When a man, even with an apparent air of playfulness, tellsme that something is going to happen, and gives a consistent consecutiveaccount of this, I have an anticipation which is not consciouslygrounded on any past experience of the value of human testimony ingeneral, or of this person's testimony in particular, but which isinstantaneous and quasi-immediate. Consequently, any error connectedwith the mental act approximates to an illusion. So far I have supposed that the anticipated event is a recurring one, that is to say, a kind of experience which has already become familiarto us. This, however, holds good only of a very few of our experiences. Our life changes as it progresses, both outwardly and inwardly. Many ofour anticipations, when first formed, involve much more than areproduction of a past experience, namely, a complex act of constructiveimagination. Our representations of these untried experiences, as, forexample, those connected with a new set of circumstances, a new socialcondition, a new mode of occupation, and so on, are clearly at the firstfar from simple processes of inference from the past. They are puttogether by the aid of many fragmentary images, restored by distinctthreads of association, yet by a process so rapid as to appear like anintuition. Indeed, the anticipation of such new experiences more oftenresembles an instantaneous imaginative intuition than a process ofconscious transition from old experiences. In the case of theseexpectations, then, there would clearly seem to be room for illusionfrom the first. But even supposing that the errors connected with the first formation ofan expectation cannot strictly be called illusory, we may see that suchsimple expectation will, in certain cases, tend to grow into somethingquite indistinguishable from illusion. I refer to expectations of_remote_ events which allow of frequent renewal. Even supposing theexpectation to have originated from some rational source, as from aconscious inference from past experience, or from the acceptance ofsomebody's statement, the very habit of cherishing the anticipationtends to invest it with an automatic self-sufficient character. To allintents and purposes the prevision becomes intuitive, by which I meanthat the mind is at the time immediately certain that something is goingto happen, without needing to fall back on memory or reflection. Thisbeing so, whenever the initial process of inference or quasi-inferencehappens to have been bad, an illusory expectation may arise. In otherwords, the force of repetition and habit tends to harden what may, inits initial form, have resembled a kind of fallacy into an illusion. And now let us proceed further. When a permanent expectation is thusformed, there arises the possibility of processes which favour illusionprecisely analogous to those which we have studied in the case ofmemory. In the first place, the habit of imagining a future event is attendedwith a considerable amount of illusion as to time or remoteness. Afterwhat has been said respecting the conditions of such error in the caseof memory, a very few words will suffice here. It is clear, then, in the first place, that the mind will tend toshorten any period of future time, and so to antedate, so to speak, agiven event, in so far as the imagination is able clearly and easily torun over its probable experiences. From this it follows that repeatedforecastings of series of events, by facilitating the imaginativeprocess, tend to beget an illusory appearance of contraction in the timeanticipated. Moreover, since in anticipation so much of each division ofthe future time-line is unknown, it is obviously easy for the expectantimagination to skip over long intervals, and so to bring together widelyremote events. In addition to this general error, there are more special errors. As inthe case of recollection, vividness of mental image suggestspropinquity; and accordingly, all vivid anticipations, to whatever causethe vividness may be owing, whether to powerful suggestion on the partof external objects, to verbal suggestion, or to spontaneous imaginationand feeling, are apt to represent their objects as too near. It follows that an event intensely longed for, in so far as theimagination is busy in representing it, will seem to approach thepresent. At the same time, as we have seen, an event much longed forcommonly appears to be a great while coming, the explanation being thatthere is a continually renewed contradiction between anticipation andperception. The self-adjustment of the mind in the attitude ofexpectant attention proves again and again to be vain and futile, and itis this fact which brings home to it the slowness of the sequences ofperceived fact, as compared with the rapidity of the sequences ofimagination. When speaking of the retrospective estimate of time, I observed that theapparent distance of an event depends on our representation of theintervening time-segment. And the same remark applies to the prospectiveestimate. Thus, an occurrence which we expect to happen next week willseem specially near if we know little or nothing of the contents of theintervening space, for in this case the imagination does not project theexperience behind a number of other distinctly represented events. Finally, it is to be remarked that the prospective appreciation of anyduration will tend to err relatively by way of excess, where the time isexceptionally filled out with clearly expected and deeply interestingexperiences. To the imagination of the child, a holiday, filled with newexperiences, appears to be boundless. Thus far I have assumed that the date of the future event is a matterwhich might be known. It is, however, obvious, from the very nature ofknowledge with respect to the future, that we may sometimes be certainof a thing happening to us without knowing with any degree ofdefiniteness when it will happen. In the case of these temporallyundefined expectations, the law already expounded holds good that allvividness of representation tends to lend the things represented anappearance of approaching events. On the other hand, there are someevents, such as our own death, which our instinctive feelings tend tobanish to a region so remote as hardly to be realized at all. So much with respect to errors in the localizing of future events. In the second place, a habit of imagining a future event or group ofevents will give play to those forces which tend to transform a mentalimage. In other words, the habitual indulgence of a certain anticipationtends to an illusory view, not only of the "when?" but also of the"how?" of the future event. These transformations, due to subtleprocesses of emotion and intellect, and reflecting the present habits ofthese, exactly resemble those by which a remembered event becomesgradually transformed. Thus, we carry on our present habits of thoughtand feeling into the remote future, foolishly imagining that at adistant period of life, or in greatly altered circumstances, we shalldesire and aim at the same things as now in our existing circumstances. In close connection with this forward projection of our present selves, there betrays itself a tendency to look on future events as answering toour present desires and aspirations. In this way, we are wont to soften, beautify, and idealize the future, marking it off from the hardmatter-of-fact present. The less like the future experience to our past experience, or the moreremote the time anticipated, the greater the scope for such imaginativetransformation. And from this stage of fanciful transformation of afuture reality to the complete imaginative creation of such a reality, the step is but a small one. Here we reach the full development ofillusory expectation, that which corresponds to hallucination in theregion of sense-perception. In order to understand these extreme forms of illusory expectation, itwill be necessary to say something more about the relation ofimagination to anticipation in general. There are, I conceive, goodreasons for saying that any kind of vivid imagination tends to pass intoa semblance of an expectation of a coming personal experience, or anevent that is about to happen within the sphere of our own observation. It has long been recognized by writers, among whom I may mention DugaldStewart, that to distinctly imagine an event or object is to feel forthe moment a degree of belief in the corresponding reality. Now, I havealready said that expectation is probably a more natural and an earlierdeveloped state of mind than memory. And so it seems probable that anymental image which happens to take hold on the mind, if not recognizedas one of memory, or as corresponding to a fact in somebody else'sexperience, naturally assumes the form of an expectation of a personalexperience. The force of the expectation will vary in general as thevividness and persistence of the mental image. Moreover, it follows, from what has been said, that this force of imagination will determinewhat little time-character we ever give to these wholly ungroundedillusions. We see, then, that any process of spontaneous imagination will tend tobeget some degree of illusory expectation. And among the agencies bywhich such ungrounded imagination arises, the promptings of feeling playthe most conspicuous part. A present emotional excitement may give to animaginative anticipation, such as that of the prophetic enthusiast, areality which approximates to that of an actually perceived object. Andeven where this force of excitement is wanting, a gentle impulse offeeling may suffice to beget an assurance of a distant reality. Theunknown recesses of the remote future offer, indeed, the field in whichthe illusory impulses of our emotional nature have their richestharvest. "Thus, from afar, each dim discover'd scene More pleasing seems than all the past hath been; And every form, that Fancy can repair From dark oblivion, glows divinely there. " The recurring emotions, the ruling aspirations, find objects forthemselves in this veiled region. Feelings too shy to burst forth inunseemly anticipation of the immediate future, modestly satisfythemselves with this remote prospect of satisfaction. And thus, therearises the half-touching, half-amusing spectacle of men and womencontinually renewing illusory hopes, and continually pushing the date oftheir realization further on as time progresses and brings no actualfruition. So far I have spoken of such expectations as refer to future personalexperience only. Growing individual experience and the enlargement ofthis by the addition of social experience enable us to frame a number ofother beliefs more or less similar to the simple expectations just dealtwith. Thus, for example, I can forecast with confidence events whichwill occur in the lives of others, and which I shall not even witness;or again, I may even succeed in dimly descrying events, such aspolitical changes or scientific discoveries, which will happen after mypersonal experience is at an end. Once more, I can believe in somethinggoing on now at some distant and even inaccessible point of theuniverse, and this appears to involve a conditional expectation, and tomean that I am certain that I or anybody else would see the phenomenon, if we could at this moment be transported to the spot. All such previsions are supposed to be formed by a process of inferencefrom personal experience, including the trustworthiness of testimony. Even allowing, however, that this was so in the first stages of thebelief, it is plain that, by dint of frequent renewal, the expectationwould soon cease to be a process of inference, and acquire an apparentlyself-evident character. This being so, if the expectation is notadequately grounded to start with, it is very likely to develop into anillusion. And it is to be added that these permanent anticipations mayhave their origin much more in our own wishes or emotional promptingsthan in fact and experience. The mind undisciplined by scientifictraining is wont to entertain numerous beliefs of this sort respectingwhat is now going on in unvisited parts of the world, or what willhappen hereafter in the distant future. The remote, and thereforeobscure, in space and in time has always been the favourite region forthe projection of pleasant fancies. Once more, besides these oblique kinds of expectation, I may form otherseemingly simple beliefs, to which the term expectation seems lessclearly applicable. Thus, on waking in the morning and finding theground covered with snow, my imagination moves backwards, as in theprocess of memory, and realizes the spectacle of the softly fallingsnow-flakes in the hours of the night. The oral communication of others'experience, including the traditions of the race, enables me to set outfrom any present point of time, and reconstruct complex chains ofexperience of vast length lying beyond the bounds of my own personalrecollection. I need not here discuss what the exact nature of such beliefs is. J. S. Mill identifies them with expectations. Thus, according to him, mybelief in the nocturnal snowstorm is the assurance that I should haveseen it had I waited up during the night. So my belief in Cicero'soratory resolves itself into the conviction that I should have heardCicero under certain conditions of time and place, which is identicalwith my expectation that I shall hear a certain speaker to-morrow if Igo to the House of Commons. [140] However this be, the thing to note isthat such retrospective beliefs, when once formed, tend to approximatein character to recollections. This is true even of new beliefs inrecent events directly made known by present objective consequences orsigns, as the snowstorm. For in this case there is commonly no consciouscomparison of the present signs with previously known signs, but merelya direct quasi-mnemonic passage of mind from the present fact to itsantecedent. And it is still more true of long-entertained retrospectivebeliefs. When, for example, the original grounds of an historicalhypothesis are lost sight of, and after the belief has hardened andsolidified by time, it comes to look much more like a recollection thanan expectation. As a matter of fact, we have seen, when studying theillusions of memory, that our personal experience does become confusedwith that of others. And one may say that all long-cherishedretrospective beliefs tend to become assimilated to recollections. Here then, again, there seems to be room for illusion to arise. Even inthe case of a recent past event, directly made known by presentobjective signs, the mind is liable to err just as in the case offorecasting an immediately approaching event. And such error has all theforce of an illusion: its contradiction is almost as great a shock asthat of a recollection. When, for example, I enter my house, and see afriend's card lying on the table, I so vividly represent to myself therecent call of my friend, that when I learn the card is an old one whichhas accidentally been put on the table, I experience a sense ofdisillusion very similar to that which attends a contradictedperception. The early crude stages of physical science abundantlyillustrate the genesis of such illusions. It may be added that if there be any feeling present in the mind at thetime, the barest suggestion of something having happened will suffice toproduce the immediate assurance. Thus, an angry person is apt to hastilyaccuse another of having done certain things on next to no evidence. Thelove of the marvellous seems to have played a conspicuous part inbuilding up and sustaining the fanciful hypotheses which mark the dawnof physical science. Verbal suggestion is a common mode of producing this semblance of arecollected event. By means of the narrative style, it vividly suggeststhe idea that the events described belong to the past, and excites theimagination to a retrospective construction of them as though they wereremembered events. Hence the power of works of fiction on the ordinarymind. Even when there is no approach to an illusion of perception, or toone of memory in the strict sense, the reading of a work of fictionbegets at the moment a retrospective belief that has a certainresemblance to a recollection. All such illusions as those just illustrated, if not afterwardscorrected, tend to harden into yet more distinctly "intuitive" errors. Thus, for example, one of the crude geological hypotheses, of which SirCharles Lyell tells us, [141] would, by the mere fact of being keptbefore the mind, tend to petrify into a hard fixed belief. And thisprocess of hardening is seen strikingly illustrated in the case oftraditional errors, especially when these fall in with our own emotionalpropensities. Our habitual representations of the remote historical pastare liable to much the same kind of error as our recollections of earlypersonal experience. The wrong statements of others and the promptingsof our own fancies may lead in the first instance to a filling up of theremote past with purely imaginary shapes. Afterwards the particularorigin of the belief is forgotten, and the assurance assumes the aspectof a perfectly intuitive conviction. The hoary traditional mythsrespecting the golden age, and so on, and the persistent errors ofhistorians under the sway of a strong emotional bias, illustrate suchillusions. So much as to simple illusions of belief, or such as involve singlerepresentations only. Let us now pass to compound illusions, whichinvolve a complex group of representations. B. _Compound Illusory Belief. _ A familiar example of a compound belief is the belief in a permanent orpersistent individual object of a certain character. Such an idea, whatever its whole meaning may be--and this is a disputed point inphilosophy--certainly seems to include a number of particularrepresentations, corresponding to direct personal recollections, to therecollections of others, and to numerous anticipations of ourselves andof others. And if the object be a living creature endowed with feelings, our idea of it will contain, in addition to these representedperceptions of ourselves or of others, a series of represented insights, namely, such as correspond to the inner experience of the being, so faras this is known or imagined. It would thus seem that the idea which we habitually carry about with usrespecting a complex individual object is a very composite idea. Inorder to see this more fully, let us inquire into what is meant by ourbelief in a person. My idea of a particular friend contains, among otherthings, numbers of vague representations of his habitual modes offeeling and acting, and numbers of still more vague expectations of howhe will or might feel and act in certain circumstances. Now, it is plain that such a composite idea must have been a very slowgrowth, involving, in certain stages of its formation, numerousprocesses of inference or quasi-inference from the past to the future. But in process of time these elements fuse inseparably: the directlyknown and the inferred no longer stand apart in my mind; my wholeconception of the individual as he has been, is, and will be, seems oneindivisible cognition; and this cognition is so firmly fixed andpresents itself so instantaneously to the mind when I think of theobject, that it has all the appearance of an intuitive conviction. If this is a fairly accurate description of the structure of thesecompound representations and of their attendant beliefs, it is easy tosee how many openings for error they cover. To begin with, myrepresentation of so complex a thing as a concrete personality mustalways be exceedingly inadequate and fragmentary. I see only a fewfacets of the person's many-sided mind and character. And yet, ingeneral, I am not aware of this, but habitually identify myrepresentation with the totality of the object. More than this, a little attention to the process by which thesecompound beliefs arise will disclose the fact that this apparentlyadequate representation of another has arisen in part by other thanlogical processes. If the blending of memory and expectation were simplya mingling of facts with correct inferences from these, it might notgreatly matter; but it is something very different from this. Not onlyhas our direct observation of the person been very limited, even thatwhich we have been able to see has not been perfectly mirrored in ourmemory. It has already been remarked that recollection is a selectiveprocess, and this truth is strikingly illustrated in the growth of ourenduring representations of things. What stamps itself on my memory iswhat surprised me or what deeply interested me at the moment. And thenthere are all the risks of mnemonic illusion to be taken into account aswell. Thus, my idea of a person, so far even as it is built up on abasis of direct personal recollection, is essentially a fragmentary andto some extent a misleading representation. Nor is this all. My habitual idea of a person is a resultant of forcesof memory conjoined with other forces. Among these are to be reckonedthe influence of illusory perception or insight, my own and that ofothers. The amount of misinterpretation of the words and actions of asingle human being during the course of a long acquaintance must be veryconsiderable. To these must be added the effect of erroneous singleexpectations and reconstructions of past experiences, in so far as thesehave not been distinctly contradicted and dissipated. All these errors, connected with single acts of observing or inferring the feelings anddoings of another, have their effect in distorting the subsequent totalrepresentation of the person. Finally, we must include a more distinct ingredient of active illusion, namely, all the complex effects of the activity of imagination as led, not by fact and experience, but by feeling and desire. Our permanentidea of another reflects all that we have fondly imagined the personcapable of doing, and thus is made up of an ideal as well as a realactually known personality. And this result of spontaneous imaginationmust be taken to include the ideals entertained by others who are likelyto have influenced us by their beliefs. [142] Enough has probably been said to show how immensely improbable it isthat our permanent cognition of so complex an object as a particularhuman being should be at all an accurate representation of the reality, how much of the erroneous is certain to get mixed up with the true. Andthis being so, we may say that our apparently simple direct cognition ofa given person, our assurance of what he is and will continue to be, isto some extent illusory. _Illusion of Self-Esteem. _ Let us now pass to another case of compound representation, where theillusory element is still more striking. I refer to the idea of selfwhich each of us habitually carries about with him. Every man's opinionof himself, as a whole, is a very complex mental product, in which factsknown by introspection no doubt play a part, but probably only a verysubordinate part. It is obvious, from what has been said about thestructure of our habitual representations of other individuals, that ourordinary representation of ourselves will be tinged with that mass oferror which we have found to be connected with single acts ofintrospection, recollections of past personal experience, and illusorysingle expectations of future personal experiences. How large an openingfor erroneous conviction here presents itself can only be understood bya reference to certain deeply fixed impulses and feelings connectedwith, the very consciousness of self, and favouring what I have markedoff as active illusion. I shall try to show very briefly that each man'sintuitive persuasion of his own powers, gifts, or importance--in brief, of his own particular value, contains, from the first, a palpableingredient of active illusion. Most persons, one supposes, have with more or less distinctconsciousness framed a notion of their own value, if not to the worldgenerally, at least to themselves. And this notion, however undefined itmay be, is held to with a singular tenacity of belief. The greater partof mankind, indeed, seem never to entertain the question whether theyreally possess points of excellence. They assume it as a matterperfectly self-evident, and appear to believe in their vaguely conceivedworth on the same immediate testimony of consciousness by which theyassure themselves of their personal existence. Indeed, the conviction ofpersonal consequence may be said to be a constant factor in most men'sconsciousness. However restrained by the rules of polite intercourse, itbetrays its existence and its energy in innumerable ways. It displaysitself most triumphantly when the mind is suddenly isolated from otherminds, when other men unite in heaping neglect and contempt on thebeliever's head. In these moments he proves an almost heroic strength ofconfidence, believing in himself and in his claims to carefulconsideration when all his acquaintance are practically avowing theirdisbelief. The intensity of this belief in personal value may be observed in verydifferent forms. The young woman who, quite independently of others'opinion, and even in defiance of it, cherishes a conviction that herexternal attractions have a considerable value; the young man who, inthe face of general indifference, persists in his habit of voluble talkon the supposition that he is conferring on his fellow-creatures thefruits of profound wisdom; and the man of years whose opinion of his ownsocial importance and moral worth is quite disproportionate to theestimation which others form of his claims--these alike illustrate theforce and pertinacity of the belief. There are, no doubt, many exceptions to this form of self-appreciation. In certain robust minds, but little given to self-reflection, the ideaof personal value rarely occurs. And then there are timid, sensitivenatures that betray a tendency to self-distrust of all kinds, and to anundue depreciation of personal merit. Yet even here traces of an impulseto think well of self will appear to the attentive eye, and one cangenerally recognize that this impulse is only kept down by some otherstronger force, as, for example, extreme sensitiveness to the judgmentof others, great conscientiousness, and so on. And however this be, itwill be allowed that the average man rates himself highly. It is to be noticed that this persuasion of personal value or excellenceis, in common, very vague. A man may have a general sense of his ownimportance without in the least being able to say wherein exactly hissuperiority lies. Or, to put it another way, he may have a strongconviction that he stands high in the scale of morally deservingpersons, and yet be unable to define his position more nearly. Commonly, the conviction seems to be only definable as an assurance of asuperlative of which the positive and comparative are suppressed. Atmost, his idea of his moral altitude resolves itself into theproposition, "I am a good deal better than Mr. A. Or Mr. B. " Now, it isplain that in these intuitive judgments on his own excellence, the manis making an assertion with respect, not only to inner subjectivefeelings which he only can be supposed to know immediately, but also toexternal objective facts which are patent to others, namely, to certainactive tendencies and capabilities, to the direction of external conductin certain lines. [143] Hence, if the assertion is erroneous, it will bein plain contradiction to others' perceptions of his powers or moralendowments. And this is what we actually find. A man's self-esteem, in alarge preponderance of cases, is plainly in excess of others' esteem ofhim. What the man conceives himself to be differs widely from whatothers conceive him to be. "Oh wad some power the giftie gie us, To see oursels as others see us!" Now, whence comes this large and approximately uniform discrepancybetween our self-esteem and others' esteem of us? By trying to answerthis question we shall come to understand still better the processes bywhich the most powerful forms of illusion are generated. It is, I think, a matter of every-day observation that children manifestan apparently instinctive disposition to magnify self as soon as thevaguest idea of self is reached. It is very hard to define this feelingmore precisely than by terming it a rudimentary sense of personalimportance. It may show itself in very different ways, taking now a moreactive form, as an impulse of self-assertion, and a desire to enforceone's own will to the suppression of others' wills, and at another timewearing the appearance of a passive emotion, an elementary form of_amour propre_. And it is this feeling which forms the germ of theself-estimation of adults. For in truth all attribution of valueinvolves an element of feeling, as respect, and of active desire, andthe ascription of value to one's self is in its simplest form merely theexpression of this state of mind. But how is it, it may be asked, that this feeling shows itselfinstinctively as soon as the idea of self begins to arise inconsciousness? The answer to this question is to be found, I imagine, inthe general laws of mental development. All practical judgments likethat of self-estimation are based on some feeling which is developedbefore it; and, again, the feeling itself is based on some instinctiveaction which, in like manner, is earlier than the feeling. Thus, forexample, an Englishman's judgment that his native country is ofparamount value springs out of a long-existent sentiment of patriotism, which sentiment again may be regarded as having slowly grown up aboutthe half-blindly followed habit of defending and furthering theinterests of one's nation or tribe. In a similar way, one suspects, thefeeling of personal worth, with its accompanying judgment, is a productof a long process of instinctive action. What this action is it is scarcely necessary to remind the reader. Everyliving organism strives, or acts as if it consciously strove, tomaintain its life and promote its well-being. The actions of plants areclearly related to the needs of a prosperous existence, individual firstand serial afterwards. The movements of the lower animals have the sameend. Thus, on the supposition that man has been slowly evolved fromlower forms, it is clear that the instinct of self-promotion must be thedeepest and most ineradicable element of his nature, and it is thisinstinct which directly underlies the rudimentary sentiment ofself-esteem of which we are now treating. This instinct will appear, first of all, as the unreflecting organizedhabit of seeking individual good, of aiming at individual happiness, andso of pushing on the action of the individual will. This impulse showsitself in distinct form as soon as the individual is brought intocompetition with another similarly constituted being. It is the forcewhich displays itself in all opposition and hostility, and it tends tolimit and counteract the gregarious instincts of the race. In the nextplace, as intelligence expands, this instinctive action becomesconscious pursuit of an end, and at this stage the thing pursuedattracts to itself a sentiment. The individual now consciously desireshis own happiness as contrasted with that of others, knowingly aims atenlarging his own sphere of action to the diminution of others' spheres. Here we have the nascent sentiment of self-esteem, on which all laterjudgments respecting individual importance are, in part at least, founded. Thus, we see that long before man had arrived at an idea of self therehad been growing up an emotional predisposition to think well of self. And in this way we may understand how it is that this sentiment ofself-esteem shows itself immediately and instinctively in the child'smind as soon as its unfolding consciousness is strong enough to graspthe first rough idea of personal existence. Far down, so to speak, belowthe surface of distinct consciousness, in the intricate formation ofganglion-cell and nerve-fibre, the connections between the idea of selfand this emotion of esteem have been slowly woven through long ages ofanimal development. Here, then, we seem to have the key to the apparently paradoxical factthat a man, with all his superior means of studying his own feelings, commonly esteems himself, in certain respects at least, less accuratelythan a good external observer would be capable of doing. In forming anopinion of ourselves we are exposed to the full force of a powerfulimpulse of feeling. This impulse, acting as a bias, enters more or lessdistinctly into our single acts of introspection, into our attempts torecall our past doings, into our insights into the meaning of others'words and actions as related to ourselves (forming the naturaldisposition to enjoy flattery), and finally into our wild dreams as toour future achievements. It is thus the principal root of that giganticillusion of self-conceit, which has long been recognized by practicalsense as one of the greatest obstacles to social action; and by art asone of the most ludicrous manifestations of human weakness. If there are all these openings for error in the beliefs we go onentertaining respecting individual things, including ourselves, theremust be a yet larger number of such openings in those still morecompound beliefs which we habitually hold respecting collections orclasses of things. A single illusion of perception or of memory maysuffice to give rise to a wholly illusory belief in a class of objects, for example, ghosts. The superstitious beliefs of mankind abundantlyillustrate this complexity of the sources of error. And in the case ofour every-day beliefs respecting real classes of objects, these sourcescontribute a considerable quota of error. We may again see this byexamining our ordinary beliefs respecting our fellow-men. A moment's consideration will show that our prevailing views respectingany section of mankind, say our fellow-countrymen, or mankind at large, correspond at best to a very loose process of reasoning. The accidentsof our personal experience and opportunities of observation, thetraditions which coloured our first ideas, the influence of our dominantfeelings in selecting for attention and retention certain aspects of thecomplex object, and in idealizing this object, --these sources of passiveand active illusion, must, to say the least, have had as much to do withour present solidified and seemingly "intuitive" knowledge as anythingthat can be called the exercise of individual judgment and reasoningpower. The force of this observation and the proof that such widely generalizedbeliefs are in part illusory, is seen in the fact that men of unlikeexperience and unlike temperament form such utterly dissimilar views ofthe same object. Thus, as Mr. Spencer has shown, [144] in looking atthings national there may be not only a powerful patriotic bias at workin the case of the vulgar Philistine, but also a distinctlyanti-patriotic bias in the case of the over-fastidious seeker afterculture. And I need hardly add that the different estimates of mankindheld with equal assurance by the cynic, the misanthropist, and thephilanthropic vindicator of his species, illustrate a like diversity ofthe psychological conditions of belief. Finally, illusion may enter into that still wider collection of beliefswhich make up our ordinary views of life and the world as a whole. Herethere reflect themselves in the plainest manner the accidents of ourindividual experience and the peculiar errors to which our intellectualand emotional conformation disposes us. The world is for us what we feelit to be; and we feel it to be the cause of our particular emotionalexperience. Just as we have found that our environment helps todetermine our idea of self and personal continuity, so, conversely, ourinner experience, our remembered or imagined joys and sorrows throw areflection on the outer world, giving it its degree of worth. Hence thecontradictory, and consequently to some extent at least illusory, viewsof the optimist and the pessimist, "intuitions" which, I have tried toshow elsewhere, are connected with deeply rooted habits of feeling, andare antecedent to all reasoned philosophic systems. If proof were yet wanted that these wide-embracing beliefs may to someextent be illusory, it would be found in the fact that they can bedistinctly coloured by a temporary mood or mental tone. As I have morethan once had occasion to remark, a feeling when present tends to colourall the ideas of the time. And when out of sorts, moody, anddiscontented, a man is prone to find a large objective cause of hisdissatisfaction in a world out of joint and not moving to his mind. It is evident that all the permanent beliefs touched on in this chaptermust constitute powerful predispositions with respect to any particularact of perception, insight, introspection, or recollection. In otherwords, these persistent beliefs, so far as individual or personal, arebut another name for those fixed habits of mind which, in the case ofeach one of us, constitute our intellectual bias, and the source of theerror known as personal equation. And it may be added that, just asthese erroneous beliefs existing in the shape of fixed prejudicesconstitute a bias to new error, so they act as powerful resisting forcesin relation to new truth and the correction of error. In comparing these illusions of belief with those of perception andmemory, we cannot fail to notice their greater compass or range, inother words, the greater extent of the region of fact misrepresented. Even if they are less forcible and irresistible than these errors, theyclearly make up for this by the area which they cover. Another thing to be observed with respect to these comprehensive beliefsis that where, as here, so many co-operant conditions are at work, thewhole amount of common objective agreement is greatly reduced. In otherwords, individual peculiarities of intellectual conformation, emotionaltemperament, and experience have a far wider scope for their influencein these beliefs than they have in the case of presentative cognitions. At the same time, it is noteworthy that error much more rapidlypropagates itself here than in the case of our perceptions orrecollections. As we have seen, these beliefs all include much more thanthe results of the individual's own experience. They offer a large fieldfor the influence of personal ascendency, of the contagion of sympathy, and of authority and tradition. As a consequence of this, the illusionsof belief are likely to be far more persistent than those of perceptionor of memory; for not only do they lose that salutary process ofcorrection which comparison with the experience of others affords, butthey may even be strengthened and upheld to some extent by such socialinfluences. And here the question might seem to obtrude itself, whether, in relationto such a fluctuating mass of belief as that just reviewed, in whichthere appears to be so little common agreement, we can correctly speakof anything as objectively determinable. If illusion and error as awhole are defined by a reference to what is commonly held true andcertain, what, it may be asked, becomes of the so-called illusions ofbelief? This question will have to be fully dealt with in the following chapter. Here it may be sufficient to remark that amid all this apparentdeviation of belief from a common standard of truth, there is a cleartendency to a rational consensus. Thought, by disengaging what is reallymatter of permanent and common cognition, both in the individual andstill more in the class, [145] and fixing this quantum of commoncognition in the shape of accurate definitions and universalpropositions, is ever fighting against and restraining the impulses ofindividual imagination towards dissociation and isolation of belief. Andthis same process of scientific control of belief is ever tending tocorrect widespread traditional forms of error, and to erect a new andbetter standard of common cognition. This scientific regulation of belief only fails where the experienceswhich underlie the conceptions are individual, variable, and subjective. Hence there is no definite common conception of the value of life and ofthe world, just because the estimate of this value must vary withindividual circumstances, temperament, etc. All that can be looked forhere in the way of a common standard or norm is a rough averageestimate. And this common-sense judgment serves practically as asufficient criterion of truth, at least in relation to such extremeone-sidedness of view as approaches the abnormal, that is to say, one ofthe two poles of irrational exaltation, or "joy-madness, " and abjectmelancholy, which, appear among the phenomena of mental disease. [146] CHAPTER XII. RESULTS. The foregoing study of illusions may not improbably have had abewildering effect on the mind of the reader. To keep the mental eye, like the bodily eye, for any time intently fixed on one object is apt toproduce a feeling of giddiness. And in the case of a subject likeillusion, the effect is enormously increased by the disturbing characterof the object looked at. Indeed, the first feeling produced by oursurvey of the wide field of illusory error might be expressed prettyaccurately by the despondent cry of the poet-- "Alas! it is delusion all: The future cheats us from afar, Nor can we be what we recall, Nor dare we think on what we are. " It must be confessed that our study has tended to bring home to the mindthe wide range of the illusory and unreal in our intellectual life. Insense-perception, in the introspection of the mind's own feelings, inthe reading of others' feelings, in memory, and finally in belief, wehave found a large field for illusory cognition. And while illusion hasthus so great a depth in the individual mind, it has a no less strikingbreadth or extent in the collective human mind. No doubt its grosserforms manifest themselves most conspicuously in the undisciplined mindof the savage and the rustic; yet even the cultivated mind is by nomeans free from its control. In truth, most of the illusions illustratedin this work are such as can be shared in by all classes of mind. In view of this wide far-reaching area of ascertained error, the mindnaturally asks, What are the real limits of illusory cognition, and howcan we be ever sure of having got beyond them? This question leads us onto philosophical problems of the greatest consequence, problems whichcan only be very lightly touched in this place. Before approachingthese, let us look back a little more carefully and gather up ourresults, reflect on the method which we have been unconsciouslyadopting, and inquire how far this scientific mode of procedure willtake us in determining what is the whole range of illusory cognition. We have found an ingredient of illusion mixed up with all the popularlyrecognized forms of immediate knowledge. Yet this ingredient is notequally conspicuous in all cases. First of all, illusion varies veryconsiderably in its degree of force and persistence. Thus, in general, apresentative illusion is more coercive than a representative; anapparent reality present to the mind is naturally felt to be moreindubitable than one absent and only represented. On the other hand, arepresentative illusion is often more enduring than a presentative, thatis to say, less easily found out. It is to be added that a good deal ofillusion is only partial, there being throughout an under-current ofrational consciousness, a gentle play of self-criticism, which keeps theerror from developing into a perfect self-delusion. This remark appliesnot only to the innocent illusions of art, but also to many of ourevery-day illusions, both presentative and representative. In manycases, indeed, as, for example, in looking at a reflection in a mirror, the illusion is very imperfect, remaining in the nascent stage. Again, a little attention to the facts here brought together will showthat the proportion of illusory to real knowledge is far from being thesame in each class of immediate or quasi-immediate cognition. Thus, withrespect to the great distinction between presentative and representativeknowledge, it is to be observed that, in so far as any act of cognitionis, strictly speaking, presentative, it does not appear to admit oferror. The illusions of perception are connected with the representativeside of the process, and are numerous just because this is so extensive. On the other hand, in introspection, where the scope of independentrepresentation is so limited, the amount of illusion is veryinconsiderable, and may in practice be disregarded. So again, to take anarrower group of illusions, we find that in the recalling of distantevents the proportion of error is vastly greater than in the recallingof near events. So much as to the extent of illusion as brought to light by ourpreceding study. Let us now glance at the conclusions obtainedrespecting its nature and its causes. _Causes of Illusion. _ Looking at illusion as a whole, and abstracting from the differences ofmental mechanism in the processes of perception, memory, etc. , we maysay that the _rationale_ or mode of genesis of illusion is very much thesame throughout. Speaking broadly, one may describe all knowledge as acorrespondence of representation with fact or experience, or as a stablecondition of the representation which cannot be disturbed by newexperiences. It does not matter, for our present purpose, whether thefact represented is supposed to be directly present, as in presentativecognition; or to be absent, either as something past or future, orfinally as a "general fact, " that is to say, the group of facts (pastand future) embodied in a universal proposition. [147] In general this accordance between our representations and facts issecured by the laws of our intellectual mechanism. It follows from theprinciples of association that our simple experiences, external andinternal, will tend to reflect themselves in perception, memory, expectation, and general belief, in the very time-connections in whichthey actually occur. To put it briefly, facts which occur together willin general be represented together, and they will be the more perfectlyco-represented in proportion to the frequency of this concurrence. Illusion, as distinguished from correct knowledge, is, to put itbroadly, deviation of representation from fact. This is due in part tolimitations and defects in the intellectual mechanism itself, such asthe imperfections of the activities of attention, discrimination, andcomparison, in relation to what is present. Still more is it due to thecontrol of our mental processes by association and habit. These forces, which are at the very root of intelligence, are also, in a sense, theoriginators of error. Through the accidents of our experience or themomentary condition of our reproductive power, representations getwrongly grouped with presentations and with one another; wronglygrouped, that is to say, according to a perfect or ideal standard, namely, that the grouping should always exactly agree with the order ofexperience as a whole, and the force of cohesion be proportionate to thenumber of the conjunctions of this experience. This great source of error has been so abundantly illustrated under thehead of Passive Illusions that I need not dwell on it further. It isplain that a passive error of perception, or of expectation, is due ingeneral to a defective grouping of elements, to a grouping whichanswers, perhaps, to the run of the individual's actual experience, butnot to a large and complete common experience. [148] Similarly, anillusory general belief is plainly a welding together of elements (hereconcepts, answering to innumerable representative images) indisagreement with the permanent connections of experience. Even apassive illusion of memory, in so far as it involves a rearrangement ofsuccessive representations, shows the same kind of defect. In the second place, this incorrect grouping maybe due, not to defectsin attention and discrimination, combined with insufficiently groundedassociation, but to the independent play of constructive imagination andthe caprices of feeling. This is illustrated in what I have calledActive Illusions, whether the excited perceptions and the hallucinationsof sense, or the fanciful projections of memory or of expectation. Herewe have a force directly opposed to that of experience. Active illusionarises, not through the imperfections of the intellectual mechanism, butthrough a palpable interference with this mechanism. It is a regroupingof elements which simulates the form of a suggestion by experience, butis, in reality, the outcome of the individual mind's extra-intellectualimpulses. We see, then, that, in spite of obvious differences in the form, theprocess in all kinds of immediate cognition is fundamentally identical. It is essentially a bringing together of elements, whether similar ordissimilar and associated by a link of contiguity, and a viewing ofthese as connected parts, of a whole; it is a process of synthesis. Andillusion, in all its forms, is bad grouping or carelessly performedsynthesis. This holds good even of the simplest kinds of error in whicha presentative element is wrongly classed; and it holds good of thosemore conspicuous errors of perception, memory, expectation, and compoundbelief, in which representations connect themselves in an order notperfectly answering to the objective order. This view of the nature and causes of illusion is clearly capable ofbeing expressed in physical language. Bad grouping of psychical elementsis equivalent to imperfect co-ordination of their physical, that is tosay, nervous, conditions, imperfect in the evolutionist's sense, as notexactly according with external relations. So far as illusions ofsuggestion (passive illusions) are concerned, the error is connectedwith organized tendencies, due to a limited action of experience. On theother hand, illusions of preconception (active illusions) usuallyinvolve no such deeply fixed or permanent organic connections, butmerely a temporary confluence of nerve-processes. [149] The nature of thephysical process is best studied in the case of errors ofsense-perception. Yet we may hypothetically argue that even in the caseof the most complex errors, as those of memory and of belief, there isimplied a deviation in the mode of connection of nervous structures(whether the connection be permanent or temporary) from the externalorder of facts. And now we are in a position to see whether illusion is ultimatelydistinguishable from other modes of error, namely, those incident toconscious processes of reasoning. It must have been plain to anattentive reader throughout our exposition that, in spite of ourprovisional distinction, no sharp line can be drawn between much ofwhat, on the surface, looks like immediate knowledge, and consciouslyderived or inferred knowledge. On its objective side, reasoning may beroughly defined as a conscious transition of mind from certain facts orrelations of facts to other facts or relations recognized as similar. According to this definition, a fallacy would be a hasty, unwarrantedtransition to new cases not identical with the old. And a good part ofimmediate knowledge is fundamentally the same, only that here, throughthe exceptional force of association and habit, the transition is toorapid to be consciously recognized. Consequently, illusion becomesidentified at bottom with fallacious inference: it may be brieflydescribed as collapsed inference. Thus, illusory perception andexpectation are plainly a hasty transition of mind from old to new, frompast to present, conjunctions of experience. [150] And, as we have seen, an illusory general belief owes its existence to a coalescence ofrepresentations of known facts or connections with products ofimagination which simulate the appearance of inferences from thesefacts. In the case of memory, in so far as it is not aided by reasoning frompresent signs, there seems to be nothing like a movement of inference. It is evident, indeed, that memory is involved in and underlies everysuch transition of thought. Illusions of memory illustrate rather aprocess of wrong classing, that is to say, of wrongly identifying thepresent mental image with past fact, which is the initial step in allinference. In this way they closely resemble those slight errors ofperception which are due to erroneous classing of sense-impressions. Butsince the intellectual process involved in assimilating mental elementsis very similar to that implied in assimilating complex groups of suchelements, we may say that even in these simple kinds of error there issomething which resembles a wrong classing of relations, something, therefore, which approximates in character to a fallacy. By help of this brief review of the nature and causes of illusion, wesee that in general it may be spoken of as deviation of individual fromcommon experience. This applies to passive illusion in so far as itfollows from the accidents of individual experience, and it still moreobviously applies to active illusion as due to the vagaries ofindividual feeling and constructive imagination. We might, perhaps, characterize all illusion as partial view, partial both in the sense ofbeing incomplete, and in the other sense of being that to which the mindby its peculiar predispositions inclines. This being so, we may veryroughly describe all illusion as abnormal. Just as hallucination, themost signal instance of illusion, is distinctly on the border-land ofhealthy and unhealthy mental life; just as dreams are in the directionof such unhealthy mental action; so the lesser illusions of memory andso on are abnormal in the sense that they imply a departure from acommon typical mode of intellectual action. It is plain, indeed, that this is the position we have been, taking upthroughout our discussion of illusion. We have assumed that what iscommon and normal is true, or answers to what is objectively real. Thus, in dealing with errors of perception, we took for granted that thecommon percept--meaning by this what is permanent in the individual andthe general experience--is at the same time the true percept. So indiscussing the illusions of memory we estimated objective time by thejudgment of the average man, free from individual bias, and apart fromspecial circumstances favourable to error. Similarly, in the case ofbelief, true belief was held to be that which men in general, or in thelong run, or on the average, hold true, as distinguished from what theindividual under variable and accidental influences holds true. And evenin the case of introspection we found that true cognition resolveditself into a consensus or agreement as to certain psychical facts. _Criterion of Illusion. _ Now, it behoves us here to examine this assumption, with the view ofseeing how far it is perfectly sound. For it may be that what iscommonly held true does not in all cases strictly answer to the real, inwhich case our idea of illusion would have to be extended so as toinclude certain common beliefs. This question was partly opened up atthe close of the last chapter. It will be found that the fulldiscussion of it carries us beyond the scientific point of viewaltogether. For the present, however, let us see what can be said aboutit from that standpoint of positive science to which we have hithertobeen keeping. Now, if by common be meant what has been shared by all minds or themajority of minds up to a particular time, a moment's inspection of theprocess of correcting illusion will show that science assumes thepossibility of a common illusion. In the history of discovery, the firstassault on an error was the setting up of the individual against thesociety. The men who first dared to say that the sun did not move roundthe earth found to their cost what it was to fly in the face of acommon, though illusory, perception of the senses. [151] If, however, by common be understood what is permanently and unshakablyheld true by men in proportion as their minds become enlightened, thenscience certainly does assume the truth of common perception and belief. Thus, the progress of the physical sciences may be described as amovement towards a new, higher, and more stable consensus of ideas andbeliefs. In point of fact, the truths accepted by men of science alreadyform a body of common belief for those who are supposed by all to havethe means of testing the value of their convictions. And the sameapplies to the successive improvements in the conceptions of the moralsciences, for example, history and psychology. Indeed, the very meaningof science appears to be a body of common cognition to which all mindsconverge in proportion to their capabilities and opportunities ofstudying the particular subject-matter concerned. Not only so, from a strictly scientific point of view it might seempossible to prove that common cognition, as defined above, must ingeneral be true cognition. I refer here to the now familiar method ofthe evolutionist. According to this doctrine, which is a scientific method in so far as itinvestigates the historical developments of mind or the order of mentalphenomena in time, cognition may be viewed as a part of the result ofthe interaction of external agencies and the organism, as an incident ofthe great process of adaptation, physical and psychical, of organism toenvironment. In thus looking at cognition, the evolutionist is makingthe assumption which all science makes, namely, that correct views arecorrespondences between internal (mental) relations and external(physical) relations, incorrect views disagreements between theserelations. From this point of view he may proceed to argue that theintellectual processes must tend to conform to external facts. Allcorrespondence, he tells us, means fitness to external conditions andpractical efficiency, all want of correspondence practical incompetence. Consequently, those individuals in whom the correspondence was morecomplete and exact would have an advantage in the struggle for existenceand so tend to be preserved. In this way the process of naturalselection, by separately adjusting individual representations toactualities, would make them converge towards a common meeting-point orsocial standard of true cognition. That is to say, by eliminating or atleast greatly circumscribing the region of individual illusion, naturalselection would exclude the possibility of a persistent common illusion. Not only so, the evolutionist may say that this coincidence betweencommon beliefs and true beliefs would be furthered by social as well asindividual competition. A community has an advantage in the strugglewith other communities when it is distinguished by the presence of theconditions of effective co-operation, such as mutual confidence. Amongthese conditions a body of true knowledge seems to be of the firstimportance, since conjoint action always presupposes common beliefs, and, to be effective action, implies that these beliefs are correct. Consequently, it may be argued, the forces at work in the action of manon man, of society on the individual, in the way of assimilating belief, must tend, in the long run, to bring about a coincidence betweenrepresentations and facts. Thus, in another way, natural selection wouldhelp to adjust our ideas to realities, and to exclude the possibility ofanything like a permanent common error. Yet once more, according to Mr. Herbert Spencer, the tendency toagreement between our ideas and the environment would be aided by whathe calls the direct process of adaptation. The exercise of a functiontends to the development of that function. Thus, our acts of perceptionmust become more exact by mere repetition. So, too, the representationsand concepts growing out of perceptions must tend to approximate toexternal facts by the direct action of the environment on our physicaland psychical organism; for external relations which are permanent will, in the long run, stamp themselves on our nervous and mental structuremore deeply and indelibly than relations which are variable andaccidental. It would seem, from all this, that so long as we are keeping to thescientific point of view, that is to say, taking for granted that thereis something objectively real answering to our perceptions andconceptions, the question of the possibility of a universal or(permanently) common illusion does not arise. Yet a little morereflection will show us that it may arise in a way. So far as thelogical sufficiency of the social consensus or common belief is acceptedas scientifically proved, it is open to suspicion on strictly scientificgrounds. The evolutionist's proof involves one or two assumptions whichare not exactly true. In the first place, it is not strictly correct to say that all illusioninvolves a practical unfitness to circumstances. At the close of ourinvestigation of particular groups of illusion, for example, those ofperception and memory, it was pointed out that many of the errorsreviewed were practically harmless, being either momentary andevanescent, or of such a character as not to lead to injurious action. And now, by glancing back over the field of illusion as a whole, we maysee the same thing. The day-dreams in which some people are apt toindulge respecting the remote future have little effect on theirconduct. So, too, a man's general view of the world is often unrelatedto his daily habits of life. It seems to matter exceedingly little, ingeneral, whether a person take up the geocentric or the heliocentricconception of the cosmic structure, or even whether he adopt anoptimistic or pessimistic view of life and its capabilities. So inadequate, indeed, does the agency of natural selection seem to beto eliminate illusion, that it may even be asked whether its tendencymay not be sometimes to harden and fix rather than to dissolve anddissipate illusory ideas and beliefs. It will at once occur to thereader that the illusion of self-esteem, discussed in the last chapter, may have been highly useful as subserving individual self-preservation. In a similar way, it has been suggested by Schopenhauer that theillusion of the lover owes its force and historical persistence to itsparamount utility for the preservation of the species. And to pass froma recurring individual to a permanently common belief, it is maintainedby the same pessimist and his followers that what they regard as theillusion of optimism, namely, the idea that human life as a whole isgood, grows out of the individual's irrational love of life, which isonly the same instinctive impulse of self-preservation appearing asconscious desire. Once more, it has been suggested that the belief infree-will, even if illusory, would be preserved by the process ofevolution, owing to its paramount utility in certain stages of moraldevelopment. All this seems to show at least the possibility of a kindof illusion which would tend to perpetuate itself, and to appear as apermanent common belief. Now, so far as this is the case, so far as illusion is useful or onlyharmless, natural selection cannot, it is plain, be counted on to weedit out, keeping it within the narrow limits of the exceptional andindividual. Natural selection gets rid of what is harmful only, and isindifferent to what is practically harmless. It may, however, still be said that the process of direct adaptationmust tend to establish such a consensus of true belief. Now, I do notwish for a moment to dispute that the growth of intelligence by thecontinual exercise of its functions tends to such a consensus: this isassumed to be the case by everybody. What I want to point out is thatthere is no scientific proof of this position. The correspondence of internal to external relations is obviouslylimited by the modes of action of the environment on the organism, consequently by the structure of the organism itself. Scientific men arefamiliar with the idea that there may be forces in the environment whichare practically inoperative on the organism, there being nocorresponding mode of sensibility. And even if it be said that ourpresent knowledge of the material world, including the doctrine of theconservation of energy, enables us to assert that there is no mode offorce wholly unknown to us, it can still be contended that theenvironment may, for aught we know, be vastly more than the forces ofwhich, owing to the nature of our organism, we know it to be composed. In short, since, on the evolution theory viewed as a scientificdoctrine, the real external world does not directly mirror itself in ourminds, but only indirectly brings our perceptions and representationsinto adjustment by bringing into adjustment the nervous organism withwhich they are somehow connected, it is plain that we cannot be certainof adequately apprehending the external reality which is here assumed toexist. Science, then, cannot prove, but must assume the coincidence betweenpermanent common intuitions and objective reality. To raise the questionwhether this coincidence is perfect or imperfect, whether all commonintuitions known to be persistent are true or whether there are any thatare illusory, is to pass beyond the scientific point of view to another, namely, the philosophic. Thus, our study of illusion naturally carriesus on from scientific to philosophic reflection. Let me try to make thisstill more clear. _Transition to Philosophic View. _ All science makes certain assumptions which it never examines. Thus, thephysicist assumes that when we experience a sensation we are acted on bysome pre-existing external object which is the cause, or at least onecondition, of the sensation. While resolving the secondary qualities oflight, sound, etc. , into modes of motion, while representing the objectvery differently from the unscientific mind, he agrees with this inholding to the reality of something external, regarding this asantecedent to and therefore as independent of the particular mind whichreceives the sense-impression. Again, he assumes the uniformity ofnature, the universality of the causal relation, and so on. Similarly, the modern psychologist, when confining himself within thelimits of positive science, and treating mind phenomenally orempirically, or, in other words, tracing the order of mental states intime and assigning their conditions, takes for granted much the same asphysical science does. Thus, as our foregoing analysis of perceptionshows, he assumes that there is an external cause of our sensations, that there are material bodies in space, which act on our sense-organsand so serve as the condition of our sense-impressions. More than this, he regards, in the way that has been illustrated in this work, thepercept itself, in so far as it is a process in time, as the normalresult of the action of such external agents on our nerve-structures, inother words, as the effect of such action in the case of the healthy andperfect nervous organism with the average organized dispositions, physical and psychical; in which case he supposes the percept tocorrespond, in certain respects at least, with the external cause asmade known by physical science. And, on the other hand, he looks on afalse or illusory percept as arising in another way not involving, asits condition, the pre-existence of a corresponding material body orphysical agent. And in this view of perception, as of other mentalphenomena, the psychologist clearly takes for granted the principle thatall mental events conform to the law of causation. Further, he assumesthat the individual mind is somehow, in a way which it is not hisprovince to inquire into, one and the same throughout, and so on. The doctrine of evolution, too, in so far as scientific--that is, aimingat giving an account of the historical and pre-historical developmentsof the collective mind in time--agrees with psychology in making likeassumptions. Thus, it conceives an external agency (the environment) asthe cause of our common sensations and perceptions. That is to say, itrepresents the external world as somehow antecedent to, and soapparently independent of, the perceptions which are adjusted to it. Andall this shows that science, while removed from vulgar unenlightenedopinion, takes sides with popular thought in assuming the truth ofcertain fundamental ideas or so-called intuitive beliefs, into the exactmeaning of which it does not inquire. When the meaning of these assumptions is investigated, we pass out ofthe scientific into the philosophic domain. Philosophy has to criticallyinvestigate the data of popular thought and of science. It has todiscover exactly what is implied in these fundamental principles. Thenit has to test their value by erecting a final criterion of truth, byprobing the structure of cognition to the bottom, and determining theproper organ of certain or accurate knowledge; or, to put it anotherway, it has to examine what is meant by reality, whether there isanything real independently of the mind, and if so, what. In doing thisit inquires not only what common sense means by its object-world clothedin its variegated garment of secondary qualities, its beauty, and so on, but also what physical science means by its cosmic mechanism of sensibleand extra-sensible matter in motion: whether there is any kind ofobjective reality belonging to the latter which does not also belong tothe former; and how the two worlds are related one to another. That isto say, he asks whether the bodies in space assumed to exist by thephysicist as the antecedent conditions of particular sensations andpercepts are independent of mind and perception generally. [152] In doing all this, philosophy is theoretically free to upset as much ofpopular belief of the persistent kind as it likes. Nor can science findfault with it so long as it keeps to its own sphere, and does notdirectly contradict any truth which science, by the methods proper toit, is able to establish. Thus, for example, if philosophy finds thatthere is nothing real independently of mind, science will be satisfiedso long as it finds a meaning for its assumed entities, such as space, external things, and physical causes. [153] The student of philosophy need not be told that these imposing-lookingproblems respecting cognition, making, up what the Germans call the"Theory of Cognition, " and the cognate problem respecting the nature ofreality, are still a long way from being settled. To-day, as in the daysof Plato and Aristotle, are argued, in slightly altered forms, the vexedquestions, What is true cognition? Is it a mere efflux from sensation, a passive conformity of representation to sensation (sensualism orempiricism)? or is it, on the other hand, a construction of activethought, involving certain necessary forms of intelligence (rationalismor intuitivism)? Again, how are we to shape to ourselves real objective existence? Is itsomething wholly independent of the mind (realism)? and if so, is thisknown to be what we--meaning here common people and men of sciencealike--represent it as being (natural realism), or something different(transfigured realism)? Or is it, on the contrary, something involvingmind (idealism)? and if so, is it a strictly phenomenal distinctionwithin our conscious experience (empirical idealism, phenomenalism), orone of the two poles of subject and object constituted by every act ofthought (rational idealism)? These are some of the questions inphilosophy which still await their final answer. Philosophy being thus still a question and not a solution, we need nothere trouble ourselves about its problems further than to remark ontheir close connection with our special subject, the study of illusion. Our brief reference to some of the principal inquiries of philosophyshows that it tends to throw doubt on things which the unreflectingpopular mind holds to be indubitable. Different schools of philosophyhave shown themselves unequally concerned about these so-calledintuitive certainties. In general it may be said that philosophy, though, as I have remarked, theoretically free to set up its ownstandard of certainty, has in practice endeavoured to give a meaningto, and to find a justification for the assumptions or first principlesof science. On the other hand, it has not hesitated, when occasionrequired, to make very light of the intuitive beliefs of the popularmind as interpreted by itself. Thus, rationalists of the Platonic typehave not shrunk from pronouncing individual impressions and objectsillusory, an assertion which certainly seems to be opposed to theassumptions of common sense, if not to those of science. On the otherhand, the modern empirical or association school is quite ready todeclare that the vulgar belief in an external world, so far as itrepresents this as independent of mind, [154] is an illusion; that theso-called necessary beliefs respecting identity, uniformity, causation, etc. , are not, strictly speaking, necessary; and so on. And in theseways it certainly seems to come into conflict with popular convictions, or intuitive certainties, as they present themselves to the unreflectingintelligence. Philosophy seems, then, to be a continuation of that process ofdetecting illusion with which science in part concerns itself. Indeed, it is evident that our special study has a very close connection withthe philosophic inquiry. What philosophy wants is something intuitivelycertain as its starting-point, some _point d'appui_ for itsconstruction. The errors incident to the process of reasoning do notgreatly trouble it, since these can, in general, be guarded against bythe rules of logic. But error in the midst of what, on the face of it, looks like intuitive knowledge naturally raises the question, Is thereany kind of absolutely certain cognition, any organ for the accurateperception of truth? And this intimate relation between the scientificand the philosophic consideration of illusion is abundantly illustratedin the history of philosophy. The errors of sense, appearing in a regionwhich to the vulgar seems so indubitable, have again and again set menthinking on the question, "What is the whole range of illusion? Isperception, as popularly understood, after all, a big hallucination? Isour life a dream?"[155] On the other hand, if our study of the wide range of illusion is fittedto induce that temper of mind which is said to be the beginning ofphilosophy, that attitude of universal doubt expressed by Descartes inhis famous maxim, _De omnibus dubitandum_, a consideration of theprocess of correction is fitted to lead the mind on to the determinationof the conditions of accurate knowledge. It is evident, indeed, that thevery conception of an illusion implies a criterion of certainty: to calla thing illusory, is to judge it by reference to some accepted standardof truth. The mental processes involved in detecting, resisting, and overcomingillusion, are a very interesting subject for the psychologist, though wehave not space here to investigate them fully. Turning to presentative, and more particularly sense-illusions, we find that the detection of anillusion takes place now by an appeal from one sense to another, forexample, from sight to touch, by way of verification;[156] now (as inMyer's experiment) by a reference from sense and presentation altogetherto representation or remembered experience and a process of reasoning;and now, (as in the illusions of art) conversely, by a transition ofmind from what is suggested to the actual sense-impression of themoment. In the sphere of memory, again, illusion is determined, as such, now by attending more carefully to the contents of memory, now by aprocess of reasoning from some presentative cognition. Finally, errorsin our comprehensive general representations of things are known to besuch partly by reasoning from other conceptions, and partly by acontinual process of reduction of representation to presentation, thegeneral to the particular. I may add that the correction of illusion byan act of reflection and reasoning, which brings the part intoconsistent relation with the whole of experience, includes throughoutthe comparison of the individual with the collective or socialexperience. [157] We may, perhaps, roughly summarize these operations by saying that theyconsist in the control of the lower automatic processes (association orsuggestion) by the higher activities of conscious will. This activity ofwill takes the form now of an effort of attention to what is directlypresent to the mind (sense-impression, internal feeling, mnemonic image, etc. ), now of conscious reflection, judgment, and reasoning, by whichthe error is brought into relation to our experience as a whole, individual and collective. It is for the philosopher to investigate the inmost nature of theseoperations as they exhibit themselves in our every-day individualexperience, and in the large intellectual movements of history. In nobetter way can he arrive at what common sense and science regard ascertain cognition, at the kinds of knowledge on which they are wont torely most unhesitatingly. There is one other relation of our subject to philosophic problems whichI have purposely left for final consideration. Our study has consistedmainly in the psychological analysis of illusions supposed to be knownor capable of being known as such. Now, the modern association schoolprofesses to be able to resolve some of the so-called intuitions ofcommon sense into elements exactly similar to those into which we havehere been resolving what are acknowledged by all as illusions. This factwould seem to point to a close connection between the scientific studyof illusion and the particular view of these fundamental intuitionstaken by one philosophic school. In order to see whether there is reallythis connection, we must reflect a little further on the nature of themethod which we have been pursuing. I have already had occasion to rise the expression "scientificpsychology, " or psychology as a positive science, and the meaning ofthis expression must now be more carefully considered. As a positivescience, psychology is limited to the function of analyzing mentalstates, and of tracing their origin in previous and more simple mentalstates. It has, strictly speaking, nothing to do with the question ofthe legitimacy or validity of any mental act. Take a percept, for example. Psychology can trace its parentage insensation, the mode in which it has come by its contents in the laws ofassociation. But by common consent, a percept implies a presentativeapprehension of an object now present to sense. Is this valid orillusory? This question psychology, as science, does not attempt toanswer. It would not, I conceive, answer it even if it were able to makeout that the whole mental content in the percept can be traced back toelementary sensations and their combinations. For the fact that in thechemistry of mind elements may combine in perfectly new forms does notdisprove that the forms thus arising, whether sentiments orquasi-cognitions, are invalid. Much less can psychology dispute thevalidity of a percept if it cannot be sure that the mind adds nothing tosensation and its grouping; that in the genesis of the perceptive state, with its intuition of something external and now present as object, nothing like a form of intelligence is superimposed on the elements ofsensation, giving to the result of their coalescence the particularunity which we find. Whether psychology as a positive science can everbe sure of this: whether, that is to say, it can answer the question, "How do we come by the idea of object?" without assuming some particularphilosophic or extra-scientific theory respecting the ultimate nature ofmind, is a point which I purposely leave open. I would contend, then, that the psychologist, in tracing the genesis ofthe percept out of previous mental experiences, no more settles thequestion, What is the object of perception? than the physicist settlesit in referring the sense-impression (and so the percept) to a presentmaterial agent as its condition. The same applies to our idea of self. I may discover the concreteexperiences which supply the filling in of the idea, and yet not settlethe question, Does intelligence add anything in the construction of theform of this idea? and still less settle the question whether there isany real unity answering to the idea. If this is a correct distinction, if psychology, as science, does notdetermine questions of validity or objective meaning but only ofgenesis, if it looks at mental states in relation only to their temporaland causal concomitants and not to their objects, it must follow thatour preceding analysis of illusion involves no particular philosophictheory as to the nature of intelligence, but, so far as accurate, consists of scientific facts which all philosophic theories ofintelligence must alike be prepared to accept. And I have little doubtthat each of the two great opposed doctrines, the intuitive and theassociational, would claim to be in a position to take up these factsinto its particular theory, and to view them in its own way. But in addition to this scientific psychology, there is anotherso-called psychology, which is, strictly speaking, philosophic. This, Ineed hardly say, is the association philosophy. It proceeds by analyzingcertain cognitions and sentiments into their elements, and straightwaydeclaring that they mean nothing more than these. That is to say, theassociationist passes from genesis to validity, from the history of aconscious state to its objective meaning. Thus, from showing that anintuitive belief, say that in causation, is not original (in theindividual or at least in the race), it goes on to assert that it is nota valid immediate cognition at all. Now, I am not concerned here toinquire into the logical value of this transition, but simply to pointout that it is extra-scientific and distinctly philosophic. If logicallyjustifiable, it is so because of some plainly _philosophic_ assumption, as that made by Hume, namely, that all ideas not derived fromimpressions are to this extent fictitious or illusory. And now we are in a position to understand the bearing of our scientificanalysis of acknowledged illusions on the associationist's treatment ofthe alleged illusions of common sense. There is no doubt, I think, thatsome of the so-called intuitions of common sense have points of analogyto acknowledged illusions. For example, the conviction in the act ofperception that something external to the mind and independent of itexists, has a certain superficial resemblance to an hallucination ofsense; and moreover, the associationist seeks to explain it by means ofthese very processes which underlie what is recognized by all assense-illusion. [158] Again, it may be said that our notions of force andof a causal nexus in the physical world imply the idea of consciousenergy as known through our muscular sensations, and so have asuspicious resemblance to those anthropomorphic illusions of which Ihave spoken under Illusions of Insight. Once more, the consciousness offreedom may, as I have suggested, be viewed as analogous in its form andits mode of origin to illusions of introspection. As a last example, itmay be said that the mind's certain conviction of the innateness of someof its ideas resembles those illusions of memory which arise through aninability to think ourselves back into a remote past having a type ofconsciousness widely unlike that of the present. But now, mark the difference. In our scientific analysis of popularlyknown illusions, we had something by which to determine the illusorycharacter of the presentation or belief. We had a popularly orscientifically accepted standard of certainty, by a reference to whichwe might test the particular _soi-disant_ cognition. But in the case ofthese fundamental beliefs we have no such criterion, except we adoptsome particular philosophic theory, say that of the associationisthimself. Hence this similarity in structure and origin cannot in itselfbe said to amount to a proof of equality of logical or objective value. Here again it must be remarked that origin, does not carry validity orinvalidity with it. [159] We thus come back to our starting-point. While there are closerelations, psychological and logical, between the scientific study ofthe ascertained facts of illusion and the philosophic determination ofwhat is illusory in knowledge as a whole, the two domains must beclearly distinguished. On purely scientific ground we cannot answer thequestion, "How far does illusion extend?" The solution of this questionmust be handed over to the philosopher, as one aspect of his problem ofcognition. One or two remarks may, perhaps, be hazarded in concluding this accountof the relation of the scientific to the philosophic problem ofillusion. Science, as we have seen, takes its stand on a stableconsensus, a body of commonly accepted belief. And this being so, itwould seem to follow, that so far as she is allowed to interest herselfin philosophic questions, she will naturally be disposed to ask, Whatbeliefs are shared in by all minds, so far as normal and developed? Inother words, she will be inclined to look at universality as the mainthing to be determined in the region of philosophic inquiry. Themetaphysical sceptic, fond of daring exploits, may break up as manyaccepted ideas as he likes into illusory _débris_, provided only he hassome bit of reality left to take his stand on. Meanwhile, the scientificmind, here agreeing with the practical mind, will ask, "Will the beliefsthus said to be capable of being shown to be illusory ever cease toexercise their hold on men's minds, including that of the iconoclasthimself? Is the mode of demonstration of such a kind as to be likelyever to materially weaken the common-sense 'intuition'?" This question would seem to be most directly answerable by an appeal toindividual testimony. Viewed in this light, it is a question for thepresent, for some few already allege that in their case philosophicreasonings exercise an appreciable effect on these beliefs. And so faras this is so, the man of scientific temper will feel that there is aquestion for him. It is evident, however, that the question of the persistence of thesefundamental beliefs is much more one for the future than for thepresent. The correction of a clearly detected illusion is, as I havemore than once remarked, a slow process. An illusion such as theapparent movement of the sun will persist as a partially developed errorlong after it has been convicted. And it may be that the fundamentalbeliefs here referred to, even if presumably illusory, are destined toexercise their spell for long ages yet. Whether this will be the case or not, whether these intuitive beliefsare destined slowly to decay and be dissolved as time rolls on, orwhether they will retain an eternal youth, is a question which we ofto-day seem, on a first view of the matter, to have no way of answeringwhich does not assume the very point in question--the truth or falsityof the belief. This much may, however, be said. The associationist whoresolves these erroneous intuitions into the play of association, admitsthat the forces at work generating and consolidating the illusory beliefare constant and permanent forces, and such as are not likely to be lesseffective in the future than they have been in the past. Thus, heteaches that the intuition of the single object in the act of perceptionowes its strength to "inseparable association, " according to which lawthe ideas of the separate "possibilities of sensation, " which are all weknow of the object, coalesce in the shape of an idea of a single unitingsubstance. He adds, perhaps, that heredity has tended, and will stilltend, to fix the habit of thus transforming an actual multiplicity intoan imaginary unity. And in thus arguing, he is allowing that theillusion is one which, to say the least of it, it will always beexceedingly difficult for reason to dislodge. In view of this uncertainty, and of the possibility, if not theprobability, of these beliefs remaining as they have remained, at leastapproximately universal, the man of science will probably be disposed tohold himself indifferently to the question. He will be inclined to say, "What does it matter whether you call such an apparently permanentbelief the correlative of a reality or an illusion? Does it make anypractical difference whether a universal 'intuition, ' of which we cannotrid ourselves, be described as a uniformly recurring fiction of theimagination, or an integral constitutive factor of intelligence? And, inconsidering the historical aspect of the question, does it not come tomuch the same thing whether such permanent mental products be spoken ofas the attenuated forms or ghostly survivals of more substantialprimitive illusions (for example, anthropomorphic representations ofmaterial objects, 'animistic' representations of mind and personality), or as the slowly perfected results of intellectual evolution?" This attitude of the scientific mind towards philosophic problems willbe confirmed when it is seen that those who seek to resolve stablecommon convictions into illusions are forced, by their very mode ofdemonstration, to allow these intuitions a measure of validity. Thus, the ideas of the unity and externality attributed to the object in theact of perception are said by the associationist to answer to a matterof fact, namely, the permanent coexistence of certain possibilities ofsensation, and the dependence of the single sensations of the individualon the presence of the most permanent of these possibilities, namely, those of the active or muscular and passive sensations of touch, whichare, moreover, by far the most constant for all minds. Similarly, theidea of a necessary connection between cause and effect, even ifillusory in so far as it expresses an _objective_ necessity, is allowedto be true as an expression of that uniformity of our experience whichall scientific progress tends to illustrate more and more distinctly. And even the idea of a permanent self, as distinct from particularfugitive feelings, is admitted by the associationist to be correct in sofar as it expresses the fact that mind is "a series of feelings whichis aware of itself as past and future. " In short, these "illusoryintuitions, " by the showing of those who affirm them to be illusory, areby no means hallucinations having no real object as their correlative, but merely illusions in the narrow sense, and illusions, moreover, inwhich the ratio of truth to error seems to be a large one. It would thus appear that philosophy tends, after all, to unsettle whatappear to be permanent convictions of the common mind and thepresuppositions of science much less than is sometimes imagined. Ourintuitions of external realities, our indestructible belief in theuniformity of nature, in the nexus of cause and effect, and so on, are, by the admission of all philosophers, at least partially and_relatively_ true; that is to say, true in relation to certain featuresof our common experience. At the worst, they can only be called illusoryas slightly misrepresenting the exact results of this experience. Andeven so, the misrepresentation must, by the very nature of the case, bepractically insignificant. And so in full view of the subtleties ofphilosophic speculation, the man of science may still feel justified inregarding his standard of truth, a stable consensus of belief, as abovesuspicion. +----------------------------------------------------------------------+|Transcribers note: In the original some footnotes read 'note[1]'and ||'note[2]'. They have been renumbered to allow readers to refer directly||to the correct footnote. |+----------------------------------------------------------------------+ INDEX. A. Abercrombie, Dr. J, 141, note[82], 278. Abnormal life, relation of, to normal, 1, 120, 121, 124, 182, 277, 284, note[132], 336; effects of amputation, 62; modification of sensibility in, 65; gross sense-illusions of, 111, hallucinations of, 118; sense of personal identity in, 289. Active, stage in perception, 27; illusion distinguished from passive, 45, 332-334. Actor. _See_ Theatre. Adaptation, illusion as want of, 124, 188, 339. Æsthetic intuition, 213; illusions of, 214. After-dreams, 144, 183. After-sensation, after-impression, 55, 115. Anæsthesia, 65. Ancestral experience, results of, 281. Animals, recognition of portraits by, 105; expectation of, 298. Anthropomorphism, 225, 360. Anticipation. _See_ Expectation. Apparitions. _See_ Hallucination. Aristotle, 130. Art, illusions of, 77, 104. Artemidoros, 129. Association, laws of, in perception, 22; in dreams, 153, 156; link of resemblance in dreams, 159; associative dispositions in dreams, 169; effect of, in insight, 221; inseparable, 359. Associationist, views of, 349, 352, 355. Attention, involved in perception 21; absence of, in sense-illusion, 39, 87; relation of, to recognition of objects, 90; expectant, 93; attitude of, in dreaming, 137, 172; to internal mental states, 194; absence of, in errors of insight, 228. Authority, influence of, in introspection, 210; in belief, 325. Autobiography, errors connected with, 276, 280. Automatic activity of centres, in hallucinations, 113; in dreams, 136, 151; automatic intellectual processes, 300, 335, 352. B. Baillarger, J. , 13, note[1], 113, note[57], 119, notes[64] and [65], 120, note[66]. Bain, Dr. A. , 32, note[12], 117, note[60], 190. Beattie, J. , 141, note[82]. Beauty, sentiment of, 206, 213. Belief, immediate, 14, 15, 294; simple and compound, 296; illusory forms of, 297; simple expectation, 297; expectation, of extra-personal experiences, 307; retrospective, 309; in persistent objects and persons, 312; self-esteem, 315; representation of classes of things, 322; representations of mankind, 322; representation of life and the world as a whole, 322; as predisposition to error, 324; amount of divergence in, 325; tendency towards convergence in, 326. Beneficial, correct knowledge as, 340; illusion as, 342. Berkeley, Bishop, 218, 349, note[154]. Binet, A. , 53, note[20]. Boismont, Brierre de, 11, note[1]. Börner, J. , 146. Braid, James, 186, 187. Brewster, Sir D. , 42, 73, 81, 116. Brücke, E. , 77, note[38]. Byron, Lord, 116. C. Carpenter, Dr. W. B. , 32, note[12], 108, 110, note[56], 186, 231, note[111], 265, note[125], 276. Castle-building, as illusory perception, 3, 99. Cause, idea of, in science, 344; reality of relation of, 347, 349, 356, 360. Change, a condition of conscious life, 252, 287, note[133]. Childhood, our recollections of, 263, 269. Children, curiosity of, 175, 180; estimate of time by, 256; confusion of dream and waking life by, 276; imagination of, 279; self-assertion of, 319; intellectual condition of, 357, note[159]. Clarke, Dr. E. H. , 117. Classification, in recognition of sensation, 21; in recognition, of object, 24; in introspective recognition, 193. Clifford, Professor W. K. , 56, note[24]. Coalescence, of sensations, 43, 52; of dream-images, 162; of internal feelings, 196; of mnemonic images, 265. Coenæsthesis, 41, 99, 145, 286, 288. Cognition, immediate or intuitive, 5, 14-16, 294; presentative and representative, 9, 13, 217, 330; nature of, in dreams, 168, 172; nature of, generally, 295, 331; philosophic problems of, 346. Colour, external reality of, 8, 37; illusory perception of, 37, 88; subjective complementary colours (colour-contrast), 67, 83. Coloured media, objects seen through, 82. Common cognition, and truth, 337; genesis and validity of, 353. Common experience distinguished from individual, 26, 27, 137, 209, 214, 336, 351; illusion as, 47, 325, 337. Common sense, intuitions of, 346, 349, 352, 357. Complementary colours, 67, 83. Concave, apparent conversion of, into convex, 84. Conjuror, tricks of, 56, 106. Consciousness, veracity of, 192, 205; inspection of phenomena of, 196; of self, 283, 285. Consensus, the standard of truth, 7, 8, 211, 325, 338, 357. Conservation of energy, 343. Construction, rational, in dreams, 170. Continuum, the perception of the world as, 52, 56, note[24]. Correction of illusion, in sense-illusion, 38, 124, 137; dreams, 182; introspection, 210; insight, 229; memory, 291; historical correction 338; intellectual processes involved in, 351. Criterion of illusion, 337. Cudworth, R. , 161 D. Deception of the senses, 19; self-deception, 200; conscious deception of others, 222. Delboeuf, J. , 175, note[97], 235, note[113]. _Delirium tremens_, 118, note[62]. Democritus, 130. De Quincey, 253, 280. Descartes, R. , 116, 350. Dickens, Charles, 277. Direction, illusory sense of, in vision, 66, 71, 73; in hearing, 72, 75. Disease. _See_ Abnormal life. Dissolution. _See_ Evolution. Doubt, starting-point in philosophy, 350. Dreams, relation of, to illusions of sense, 18, 130; and waking experience, 127; theories of, 128; physiology of, 131; extent of, in sleep, 132; psychological conditions of, 136; excitants of, 139, 143; exaggeration in, 147; symbolism of, 149; as results of automatic activity of centres, 151; as results of association, 153; structure of, 156; incoherent, 156; coherent, 161; action of feeling in, 164; play of associative dispositions in, 168; co-operation of attention and intelligence in, 172; limits of intelligence in, 180; after-dreams, 183, 274; relation of, to hypnotic condition, 185; experience of, in relation to errors of memory, 273. E. Eccentricity, law of, 59. Ego. _See_ Self. Emotion, and illusion of perception, 103; and hallucination, 115; and bodily sensations, 150; control of dreams by, 164; introspection of, 199; and illusion of introspection, 203; and æsthetic intuition, 213; and illusion of memory, 270; and illusion of belief, 306, 324; and cognition generally, 357, note[159]. Empiricism, philosophic, 348. _Ennui_, and sense of time, 250. Environment, sources of sense-illusion in, 47, 48, 70; view of, in mental disease, 290, 326; view of, in normal life, 323; action of, in assimilating belief, 339. Error, immediate and mediate, 6, 334. Esquirol, J. E. D. , 12, note[2]. Evolution, relation of, to dissolution, 122; of power of introspection, 209; of power of insight, 230; and self-assertion, 320; evolutionist's view of error, 339; doctrine of, as science, 346. Exaggeration, in interpretation of sensations, 65; in dream-interpretation, 147; in memory, 269. Expectation, preliminary to perception, 30; and illusory perception, 93, 102, 106; nature of, 295; and memory, 298; of new experience, 301; of remote events, 302; measurement of duration in, 302; action of imagination in, 305; extension of meaning of, 307, 308. Experience, effect of, in perception, 22, 68, 85, 86, 91; external and internal, 194, 210; revivals of waking, in dreams, 152; effects of present, on retrospection, 267; anticipation of new, 301. External world. _See_ World. F. Fallacy and illusion 6, 335; of testimony, 265. Familiarity, sense of, in new objects, 272, 281. Fechner, G. T. , 51. Ferrier, Dr. , 32, note[12], 58, note[26]. Fiction, as producing illusion, 278, 279, 311. Fitness. _See_ Adaptation. Flattery, _rationale_ of, 200, 222. Forgetfulness and illusion, 278, 279, 311. Free-will, doctrine of, 207, 342, 356. Future. _See_ Expectation. G. Galton, F. , 117. Ghosts. _See_ Hallucination. Goethe, 116, 117, 280 and note[131]. Griesinger, W. , 13, note[2], 63, note[31], 66, note[32], 115, 118, note[62], 119, note[64], 120, note[66], 290, note[135], 327, note[146]. Gruithuisen, 143, 144. Gurney, E. , 224, note[109]. H. Hall, G. S. , 186, note[102]. Hallucination, and illusion, 11, 109, 111, 112, 121; and subjective sensation, 63, 109, 121; sensory and motor, 66; nervous conditions of, 112-114; incomplete and complete, 113; as having either central or peripheral origin, 113; causes of, classified, 115; in sane condition, 116; in insanity, 118; visual and auditory, 119; dreams regarded as, 139, 151; hypnagogic, 143; after-dreams and ghosts, 183; of memory, 271; relation of, to errors of belief, 322; intuition of external world regarded as, 355. Happiness, feeling of, 200. Harmful, illusion as, 188, 229, 292, 339. Harmless, illusions as, 124, 292, 341. Hartley, D. , 139, 256, note[124], 279. Hearing, as mode of perception, 34, 48; localization of impression in, 60; sense of direction in, 72; activity of, in sleep, 140; and muscular sense, 171. Heidenhain, Dr. , 186-188. Helmholtz, H. , 22, 23, note[7], 44, 51, 54 and note[22], 55, note[23], 57, 67, note[33], 78, note[39], 80, 85, note[43], 88, 90, 207, note[105]. Heraclitus, 137. Heredity, and illusion of memory, 280; action of, in perpetuating intuition, 359. Hering, E. , 67, note[33]. Hodgson, Shadworth H. , 347, note[153]. Holland, Sir H. , 277. Hood, Thomas, 146. Hope, illusory. _See_ Expectation. Hoppe, Dr. J. I. , 51, 58, note[26]. Horwicz, A. , 145, note[85]. Hume, D. , 355. Huxley, Professor T. , 119, note[1]. Hyperæsthesia, 65. Hypnotism, 185. Hypochondria, 65. Hypothesis, as illusory, 310, 311. I. Idealism, 348. Identity, cases of mistaken, 267. Identity, personal, confusion of, in dreams, 163; consciousness of, 241, 267, 282, 285; illusory forms of, 283; gross disturbances of, in normal life, 287; in abnormal life, 289; momentary confusions of, 293. Illusion, definition of, 1; varieties of, 9; extent of, 328; _rationale_ of, 331, 337. Image (physical). _See_ Reflection. Image (mental), in perception, 22; seat of, 32; in dreams, 138; mnemonic, 236. Imagination, play of, in perception, 95, 99; and sense-illusion, 106; nature of, in dreaming, 136, 161; as antecedent of dream, 152, 158; as poetic interpretation of nature, 224; memory corrupted by effect of past, 264, 273, 277; present, creating the semblance of recollection, 267, 271; play of, in expectation, 305; as element of illusion generally, 333. Immediate. _See_ Cognition. Individual, and common experience, 26, 27, 137, 209, 214, 336; dream-experience as, 44, 68; internal experience as, 209; memory as, 232; belief and truth, 338. Inference, and immediate knowledge, 6, 334; in perception, 22, 26, 68; in belief, 295. Innate, recollection as, 280; principles, 295, 356. Insane, sense-illusions of, 63, 65, 111; hallucinations of, 118; dreaming and state of, 182; mnemonic illusions of, 278, 289; beliefs of, 327. Insight, nature of, 217; illusions of, defined, 220; passive illusions of, 220; histrionic illusion, 222; active illusions of, 223; poetic interpretation of nature, 224; value of faculty of, 228. Interpretation, in correct perception, 22; of impression and experience, 70; and volition, 95; and fixed habits of mind, 101; and temporary attitude of mind, 102; of sensations in dreams, 137, 147; of internal feelings, 203; of others' feelings, 217; of nature by poet, 225; recollection as, 242. Introspection, nature of, 14, 189; illusory forms of, 190; confusion of inner and outer experiences, 194; inaccurate inspection of feelings, 196; presentation and representation confused, 199; feelings and inferences from these, 203; moral self-scrutiny, 204; philosophic, 205; value of, 208. Intuition. _See_ Cognition. Intuitivism, 348. J. Jackson, Dr. J. Hughlings, 27, note[9], 33, 123, note[67]. Johnson, Dr. , 116. K. _Klang_, as compound sensation, 53. Knowledge. _See_ Cognition. L. Language, function of, 195. Leibnitz, 133. Lélut, L. F. , 120, note[66]. Lessing, G. E. , 133, note[73]. Leuret, 290, note[135]. Lewes, G. H. , 28, 32, note[12], 52, note[30], 62, note[1], 68, note[35], 89, note[45], 115, note[58], 150. Life, our estimate of, 323, 326, 327. Light, sensation and perception of, 59; effects of reflection and refraction, of, 73; representation, of, in painting, 88, 91; action of, in sleep, 140. Localization, as local discrimination of sensations, 52; as localizing of sensations, 59, 60; illusory, 61, 82; in hallucination, 118, 119; in dreaming, 148; of events in time, in memory, 238, 245; in expectation, 304. Locke, 133, note[73]. Lotze, H. , 60, note[29]. Lover, illusion of, 224, 227, 342. Luminosity of painting, 88, 91. Lustre, as compound sensation, 54. Lyell, Sir Charles, 311. M. Magic, arts of, 73. Magnitude, apparent, in vision, 75, note[37]; perception of, in pictorial art, 88, 91; of time-intervals, 245, 249; recollection of, 268. Malebranche, 116. Mankind, our views of, 322. Matter. _See_ World (material). Maudsley, Dr. H. , 32, note[12]. Maury, A. , 140, 143, 153, note[92], 159, 163, note[94], 173. Mayer, Dr. A. , 66, note[32]. Measurement, subjective, of time, 245. Media, coloured, illusions connected with presence of, 82. Memory, nature of, 9, 13, 231; veracity of, 232, 290; defined, 234; psychology of, 236; physiology of, 237; localization of events in, 238; and sense of personal identity, 241, 283; illusions of, 241; illusory localization, 245, 256; distortions of, 261; hallucinations of, 271; illusions respecting personal identity, 283; relation of, to belief, 295; compared with expectation, 297; and inference, 335. Metempsychosis, 294. Meyer, H. , 83, 144. Mill, J. S. , 298, note[138], 309. Mirrors, as means of delusion, 73. Misanthropist, 2, 323. Mitchell, Dr. Weir, 62. Monomania, 111. Moral, intuition, 216; self-inspection, 204. Motor illusions. _See_ Muscular sense. Movement, apparent, 50, 57, 73, 81, 95, 107; in dreams, 142, 154. Müller, Johannes, 58, note[27], 100, 117, 143. _Muscæ volitantes_, 118, note[62]. Muscular sense, in perception, 23; illusions connected with, 50, 57, 62, 66; co-operation, of, in dreams, 142, 154. Music, subjective interpretation of, 223. N. Natural selection, effect of, in eliminating error, 340. Nature, personification of, 224; uniformity of, 344, 360. Necessity, idea of, 349, 360. Nervous system, and conditions of perception, 31; connections of, 32, 169; function of, and force of stimulus, 47, 50; prolonged activity of, 55; specific energy of, 58; variations in state of, 64; fatigue of, 65, 115; disease of, _ibid. _; nervous conditions of hallucination, 112, 115; nervous dissolution and evolution, 122; condition of, in sleep, 131; in hypnotic condition, 186; nervous conditions of memory, 237; nervous conditions of illusion in general, 334. Normal life, relation of, to abnormal, 1, 121, 124, 182, 277, 284, note[132]; hallucinations of, 116. O. Object, nature of, 36, 353. Objective and subjective experience, 26, 27, 137, 214. Old age, dreams how regarded in, 276. Oneirocritics, 129. Opera, illusion connected with, 104. Optimism, 323, 327, 342. Organic sensations, discrimination of, 41; interpretation of, 99; in sleep, 145, 148. Organism, conditions of illusion in, 47, 50; relation of our conception of the universe to sensibilities of, 343. Orientation, 125, 138. P. Pain, recollection of, 264, 270. Painting, representation of third dimension by, 77; apparent movement of eye in portrait, 81; discrepancies between, and object in magnitude and luminosity, 88; realization of, and mental preparation, 105; realization of, by animals, 105. Paræsthesia, 68. Paralysis of ocular muscles, 66. Passive, and active factor in perception, 27; and active illusion, 45. Percept, 22; and sense-impression, 59. Perception, a form of immediate knowledge, 10, 13, 17, 18; external and internal, 14; philosophy of, 14, 20, 22, 36, 346, 348, 353, 355, 359; illusions of, 19, 35; psychology of, 20; and inference, 22, 26, 76; physiological conditions of, 31. Persistent objects, representation of, 312. Persistent self. _See_ Personal identity. Personal equation, in perception, 101; in æsthetic intuition, 214; in memory, 292; in belief, 324. Personal identity, consciousness of, 241, 282, 285; illusions connected with, 283; disturbances in sense of, 287; sense of, in insanity, 289; momentary confusions of, 293; philosophic problem of, 285, 354, 360. Personification of nature, 224. Perspective, linear, 79, 97, 98; aerial, 80; of memory, 245. Pessimism, 323, 327. Phenomenalism, 348. Philosophy, conception of illusion by, 7, 36, 205, 285, 349; of mind, 132, 285, 344, 348; as theory of knowledge, 295, 346; and science, 346, 348; and common sense, 347, 349; problems of, 347. Phosphenes, 58. Physical science. _See_ Science. Plato, 281. Platonists, 349. Pleasure, feeling of, 200; recollection of, 264, 270. Plutarch, 133, note[73]. Poetry, lyrical and dreams, 164; misinterpretation of, 223; personification, 224. Points, discrimination of, 52. Poisons, action of, 115. Pollock, F. , 184, note[101]. Pollock, W. H. , 184. Predisposition, action of, in perception, 44, 101, 102; in æsthetic intuition, 215; in insight, 223; in recollection, 268; in belief, 305, 319; belief as, 324. Prejudice. _See_ Predisposition. Prenatal experience, recollection of, 281. Preperception, 27; illusions connected with, 44, 93; voluntary, 95; result of habit of mind, 101; result of temporary conditions, 102; as sub-expectation, 102; as definite expectation, 106. Presentation and representation, 9, 10, 13, 14, 192, 234, 329, 330. Projection, outward, of sensations, 63; of mental image, 111, 112; of solid form on flat, 79, 81, 96. Prophetic, dreams as, 129, 147, note[88]; enthusiast, 307. Psychology, popular and scientific, 9, 10; distinguished from philosophy, 14, 36, 345, 352; introspective method of, 208; as a kind of philosophy, 305. Public events, localization, of, by memory, 258. R. Radestock, P. , 130, note[71], 132, note[72], 134, note[75], 140, 141, 149, note[90], 162, 182, 275. Rationalism, philosophic, 348. Realism, 348. Reality, nature of, 36, 346. Recognition, and perception, 24, 25; illusions of, 87; and memory, 234. Reflection (of light), illusions connected with, 73, 83. Refraction and optical illusion, 73. Relative, sensation as, 64; attention to magnitude and brightness as, 91; estimate of duration as, 249. Relief, illusory perception of, 75, 96. Representation and presentation, 9, 10, 13, 14, 192. Retrospection. _See_ Memory. Ribot, T. , 238, note[114], 290, note[135]. Richter, J. P. , 143. Robertson, Professor G. C. , 35, note[14]. Romanes, G. J. , 105, note[2], 250, note[122]. Rousseau, 280. S. Savage, dream theory of, 128; idea of nature of, 225. Scherner, C. A. , 140, 149. Schopenhauer, A. , 145, 342. Schroeder, H. , 85. Science, philosophy and, 8, 36, 285, 344; conception of the material world in physical, 36, 343, 346, 347; and common cognition, 338, 357. Scott, Sir W. , 116, 125. Secondary qualities, 36, 344. Selection, process of, in perception, 95; in dreams, 174; in memory, 257, 263. Self, confusion of, in dreams, 163; introspective knowledge of, 192; self-deception, 200; identity of, 241, 282, 285; confusion of present and past, 267, 284; disturbances in recognition of, 287, 289; momentary confusions of, 295; confusion of present and future, 305. Self-esteem, illusion of, 315; origin of, 319; utility of, 342. Self-preservation, 320. Sensation, element in perception, 20; discrimination and classification of, 21; interpretation of, 22; inattention to, 39, 87; modified by central reaction, 39, 87, 89, 91; confusion of novel, 40; indistinct, 41; misinterpretation of, 44; relation of, to stimulus, 46, 50; limits to discrimination of, 52; after-impression, 55; subjective, 59, 62, 107, 143; localization of, 59. Sensibility, limits of, 50; variations of, 64. Sensualism, philosophic, 348. Shadow, cast, 77. Shakespeare, 3. Sight, mode of perception, 19, 33, 34, 48, 49; local discrimination in, 52; single vision, 54; localization of impression in, 60; in sleep, 139; images of, in sleep, 150, 154. Single, vision, 54; touch, 72. Sleep, mystery of, 127; physiology of, 131. Sleight of hand. _See_ Conjuror. Smell, as mode of perception, 34, note[14]; localization of impression in, 60; subjective sensations of, 108; in sleep, 141; and taste, 171. Solidity, illusory perception of, 75, 96. Space, representation of, 207. Specific energy of nerves, 58. Spectra, ocular, etc. _See_ Subjective sensation. Spencer, Herbert, 32, note[12], 128, note[69], 323, 340. Spinoza, 143, 184. Spiritualist _séances_, 103, 107, 123, 265. Stereoscope, 75. Stewart, Dugald, 172, 306. Stimulus, qualitative relation of, to sensations, 46, 58, 67; quantitative relation of, to sensation, 50, 64; after-effect of, 55; prolonged action of, 56; subjective or internal, 62; exceptional relation of, to organ, 70; action of, in sleep, 135, 139, 143; in hypnotic condition, 186. Strümpell, L. , 144, 147, note[89]. Subjective, experience, 26, 27, 137, 214; movement, 51, 57; sensation, 59, 62, 107, 113, 121, 143. Suggestion, by external circumstances, 30, 44, 89, 91, 267; verbal, 30, 106, 188, 215, 268, 301, 310. Symbol, dream as, 129, 149. Sympathy, basis of knowledge, 223; and illusion of insight, 223; and illusion of memory, 277; and momentary illusion, 293. T. Taine, H. , 60, note[29], 108, note[54], 117, note[59], 137, 298, note[137], 356, note[158]. Taste, æsthetic. _See_ Æsthetic intuition. Taste, localization of impression in, 60; subjective sensations of, 63; variations in sensibility, 68; activity of, in sleep, 141; and smell, 171. Temperament, a factor in sense-illusion, 101; in dreams, 137; in illusory belief, 325; in illusion generally, 334, note[149]. Temperature, sense of, 65. Tennyson, A. , 226. Testa, A. J. , 131. Testimony, of consciousness, 205; fallacies of, 265; to identity, 267. Thaumatrope, 56. Theatre, illusion of the, 104, 222; self-deception of the actor, 200. Thompson, Professor S. P. , 51, note[17]. Thought, in relation to belief, 326. Time, retrospective idea of, 239, 246, 250; constant error in estimate of, 245; subjective estimate of, 249; contemporaneous estimate of, 250; sense of, in insanity, 290; prospective estimate of, 303. Touch, as form of perception, 33, 34, 49; local discrimination in, 52; subjective sensations of, 62; variations in sensibility of, 65; in sleep, 141. Transformation, in perception, 94; of images in dreams, 163; in memory, 262, 267; in expectation, 305. Trick. _See_ Conjuror. Tuke, Dr. , 110. Tylor, E. B. , 128, note[69]. U. Unconscious, inference, 22, 68, 269, 335, note[150]; mental activity, 133, 235; impressions, 41, 152. Useful. _See_ Beneficial. V. Vanity. _See_ Self-esteem. Venn, J. , 299, note[139]. Ventriloquism, 82. Verification, of sense-impression, 38, 351; of self-inspection, 210; of memory, 291. Verisimilitude, in art, 80, 88; in theatrical representation, 104; in dreams, 168. Vierordt, 245. Vision. _See_ Sight. Visions, 1, 110; dreams regarded as, 128, 131. Vital sense. _See_ Coenæsthesis. Voice, internal, 119, 194; activity of, in dreams, 155. Volition, and perception, 95; absence of, during sleep, 137, 172; co-operation of, in correction, of illusion, 352. Volkelt, J. , 172. W. Weber, E. H. , 43. Weinhold, Professor, 186. Wetness, perception of, 53. Wheatstone, Sir C, 75. Wheel of life, 56. Will. _See_ Volition. Wordsworth, W. , 281. World, our estimate of, 323, 326, 327; scientific conception of material, 8, 36, 343, 344; reality of external, 344-346, 349, 353, 355, 360. Wundt, Professor, W. 13, note[2], 31, note[11], 32, note[12], 58, note[27], 67, note[34], 75, 93, note[47], 118, note[63], 136, note[77], 139, 143, 177, 246, 247, note[119], 251, 252, 254. THE END FOOTNOTES: [1] A history of the distinction is given by Brierre de Boismont, in hiswork _On Illusions_ (translated by R. T. Hulme, 1859). He says thatArnold (1806) first defined hallucination, and distinguished it fromillusion. Esquirol, in his work, _Des Maladies Mentales_ (1838), may besaid to have fixed the distinction. (See Hunt's translation, 1845, p. 111. ) [2] This fact has been fully recognized by writers on the pathology ofthe subject; for example, Griesinger, _Mental Pathology andTherapeutics_ (London, 1867), p. 84; Baillarger, article, "DesHallucinations, " in the _Mémoires de l'Académie Royale de Médecine_, tom. Xii. P. 273, etc; Wundt, _Physiologische Psychologie_, p. 653. [3] I here touch on the distinction between the psychological and thephilosophical view of perception, to be brought out more fullyby-and-by. [4] It might even be urged that the order here adopted is scientificallythe best, since sense-perception is the earliest form of knowledge, introspected facts being known only in relation to perceived facts. Butif the mind's knowledge of its own states is thus later in time, it isearlier in the logical order, that is to say, it is the most strictlypresentative form of knowledge. [5] Here and elsewhere I use the word "impression" for the whole complexof sensation which is present at the moment. It may, perhaps, not beunnecessary to add that, in employing this term, I am making noassumption about the independent existence of external objects. [6] Psychological usage has now pretty well substituted the term "image"for "idea, " in order to indicate an individual (as distinguished from ageneral) representation of a sensation or percept. It might, perhaps, bedesirable to go further in this process of differentiating language, andto distinguish between a sensational image, _e. G. _ the representation ofa colour, and a perceptional image, as the representation of a colouredobject. It may be well to add that, in speaking of a fusion of an imageand a sensation, I do not mean that the former exists apart for a singleinstant. The term "fusion" is used figuratively to describe the union ofthe two sides or aspects of a complete percept. [7] This impulse to fill in visual elements not actually present isstrikingly illustrated in people's difficulty in recognizing the gap inthe field of vision answering to the insensitive "blind" spot on theretina. (See Helmholtz, _Physiologische Optik_, p. 573, _et seq. _) [8] This relation will be more fully discussed under the head of"Memory. " [9] I adopt this distinction from Dr. J. Hughlings Jackson. See hisarticles, "On Affections of Speech from Diseases of the Brain, " in_Brain_, Nos. Iii. And vii. The second stage might conveniently be namedapperception, but for the special philosophical associations of theterm: _Problems of Life and Mind_, third series, p. 107. This writeremploys the word "preperception" to denote this effect of previousperception. [10] Such verbal suggestion, moreover, acting through asense-impression, has something of that vividness of effect whichbelongs to all excitation of mental images by external stimuli. [11] See Wundt, _Physiologische Psychologie_, p. 723. [12] For a confirmation of the view adopted in the text, see ProfessorBain, _The Senses and the Intellect_, Part II. Ch. I. Sec. 8; HerbertSpencer, _Principles of Psychology_, vol. I. P. 234, _et passim_; Dr. Ferrier, _The Functions of the Brain_, p. 258, _et seq. _; ProfessorWundt, _op. Cit. _, pp. 644, 645; G. H. Lowes, _Problems of Life andMind_, vol. V. P. 445, _et seq. _ For an opposite view, see Dr. Carpenter, _Mental Physiology_, fourth edit. , p. 220, etc. ; Dr. Maudsley, _The Physiology of Mind_, ch. V. P. 259, etc. [13] See note, p. 22. [14] Touch gives much by way of interpretation only when an individualobject, for example a man's hat, is recognized by aid of this sensealone, in which case the perception distinctly involves the reproductionof a complete visual percept. I may add that the organ of smell comesnext to that of hearing, with respect both to the range and definitenessof its simultaneous sensations, and to the amount of informationfurnished by these. A rough sense of distance as well as of direction isclearly obtainable by means of this organ. There seems to me no reasonwhy an animal endowed with fine olfactory sensibility, and capable of ananalytic separation of sense elements, should not gain a roughperception of an external order much more complete than our auditoryperception, which is necessarily so fragmentary. This suppositionappears, indeed, to be the necessary complement to the idea firstbroached, so far as I am aware, by Professor Croom Robertson, that tosuch animals, visual perception consists in a reference to a system ofmuscular feelings defined and bounded by strong olfactory sensations, rather than by tactual sensations as in our case. [15] It may be said, perhaps, that the exceptional direction ofattention, by giving an unusual intensity to the impression, causes usto exaggerate it just as in the case of a novel sensation. An effort ofattention directed to any of our vague bodily sensations easily leads usto magnify its cause. A similar confusion may arise even in directvision, when the objects are looked at in a dim light, through a want ofproper accommodation. (See Sir D. Brewster, _op. Cit. _, letter i) [16] They might also be distinguished as objective and subjectiveillusions, or as illusions _a posteriori_ and illusions _a priori_. [17] _Die Schein-Bewegungen_, von Professor Dr. J. I. Hoppe (1879); _cf. _an ingenious article on "Optical Illusions of Motion, " by ProfessorSilvanus P. Thompson, in _Brain_, October, 1880. These illusionsfrequently involve the co-operation of some preconception orexpectation. For example, the apparent movement of a train when we arewatching it and expecting it to move, involves both an element ofsense-impression and of imagination. It is possible that the illusion oftable-turning rests on the same basis, the table-turner being unaware ofthe fact of exerting a certain amount of muscular force, and vividlyexpecting a movement of the object. [18] _Physiologische Optik_, p. 316. [19] It is plain that this supposed error could only be brought underour definition of illusion by extending the latter, so as to includesense-perceptions which are contradicted by reason employing idealizedelements of sense-impression, which, as Lewes has shown (_Problems ofLife and Mind_, i. P. 260), make up the "extra-sensible world" ofscience. [20] An ingenious writer, M. Binet, has tried to prove that the fusionof homogeneous sensations, having little difference of local colour, isan illustration of this principle. (See the _Revue Philosophique_, September, 1880. ) [21] Even the fusion of elementary sensations of colour, on thehypothesis of Young and Helmholtz, in a seemingly simple sensation maybe explained to some extent by these circumstances, more especially theidentity of local interpretation. [22] The perception of lustre as a single quality seems to illustrate alike error. There is good reason to suppose that this impression arisesthrough, a difference of brightness in the two retinal images due to theregularly reflected light. And so when this inequality of retinalimpression is imitated, as it may easily be by combining a black and awhite surface in a stereoscope, we imagine that we are looking at onelustrous surface. (See Helmholtz, _Physiologische Optik_, p. 782, etc. , and _Populäre wissenschaftliche Vorträge_, 2tes Heft, p. 80. ) [23] The conditions of the production of these double images have beenaccurately determined by Helmholtz, who shows that the coalescence ofimpressions takes place whenever the object is so situated in the fieldof vision as to make it practically necessary that it should berecognized as one. [24] These illusions are, of course, due in part to inattention, sinceclose critical scrutiny is often sufficient to dispel them. They arealso largely promoted by a preconception that the event is going tohappen in a particular way. But of this more further on. I may add thatthe late Professor Clifford has argued ingeniously against the idea ofthe world being a continuum, by extending this idea of the wheel oflife. (See _Lectures and Essays_, i. P. 112, _et seq. _) [25] It is supposed that in the case of every sense-organ there isalways some minimum forces of stimulus at work, the effect of which onour consciousness is _nil_. [26] See Helmholtz, _Physiologische Optik_, p. 603. Helmholtz'sexplanation is criticised by Dr. Hoppe, in the work already referred to(sec. Vii), though I cannot see that his own theory of these movementsis essentially different. The apparent movement of objects in vertigo, or giddiness, is probably due to the loss, through a physical cause, ofthe impressions made by the pressure of the fluid contents of the ear onthe auditory fibres, by which the sense of equilibrium and of rotationis usually received. (See Ferrier, _Functions of the Brain_, pp. 60, 61. ) [27] I do not need here to go into the question whether, as JohannesMüller assumed, this is an original attribute of nerve-structure, orwhether, as Wundt suggests, it is due simply to the fact that certainkinds of nervous fibre have, in the course of evolution, been slowlyadapted to one kind of stimulus. [28] I here refer to what is commonly supposed to be the vague innatedifference of sensation according to the local origin, before this isrendered precise, and added to by experience and association. [29] The illusory character of this simple mode of perception is seenbest, perhaps, in the curious habit into which we fall of referring asensation of contact or discomfort to the edge of the teeth, the hair, and the other insentient structures, and even to anything customarilyattached to the sentient surface, as dress, a pen, graving tool, etc. Onthese curious illusions, see Lotze, _Mikrokosmus_, third edit. , vol. Ii. P. 202, etc. ; Taine, _De l'Intelligence_, tom. Ii. P. 83, _et seq. _ [30] Quoted by G. H. Lewes, _Problems of Life and Mind_, third series, p. 335. These illusions are supposed to involve an excitation of thenerve-fibres (whether sensory or motor) which run to the muscles andyield the so-called muscular sensations. [31] It is brought out by Griesinger (_loc. Cit. _) and the other writerson the pathology of illusion already quoted, that in the case ofsubjective sensations of touch, taste, and smell, no sharp line can bedrawn between illusion and hallucination. [32] For a fuller account of these pathological disturbances ofsensibility, see Griesinger; also Dr. A. Mayer, _Die Sinnestäuschungen_. [33] Helmholtz, _op. Cit. _, p. 600, _et seq. _ These facts seem to pointto the conclusion that at least some of the feelings by which we knowthat we are expending muscular energy are connected with the initialstage of the outgoing nervous process in the motor centres. In otherpathological conditions the sense of weight by the muscles of the armsis similarly confused. [34] Wundt (_Physiologische Psychologie_, p. 653) would exclude fromillusions all those errors of sense-perception which have theirfoundation in the normal structure and function of the organs of sense. Thus, he would exclude the effects of colour-contrast, _e. G. _ theapparent modification of two colours in, juxtaposition towards theircommon boundary, which probably arises (according to E. Hering) fromsome mutual influence of the temporary state of activity of adjacentretinal elements. To me, however, these appear to be illusions, sincethey may be brought under the head of wrong _interpretations_ ofsense-impressions. When we see a grey patch as rose-red, as though itwere so independently of the action of the complementary lightpreviously or simultaneously, that is to say, as though it would appearrose-red to an eye independently of this action, we surely misinterpret. [35] Quoted by G. H. Lewes, _loc. Cit. _, p. 257. [36] The subject of the perception of movement is too intricate to bedealt with fully here. I have only touched on it so far as necessary toillustrate our general principle. For a fuller treatment of the subject, see the work of Dr. Hoppe, already referred to. [37] The perception of magnitude is closely connected with that ofdistance, and is similarly apt to take an illusory form. I need onlyrefer to the well-known simple optical contrivances for increasing theapparent magnitude of objects. I ought, perhaps, to add that I do notprofess to give a complete account of optical illusions here, but onlyto select a few prominent varieties, with a view to illustrate generalprinciples of illusion. For a fuller account of the various mechanicalarrangements for producing optical illusion, I must refer the reader tothe writings of Sir D. Brewster and Helmholtz. [38] Painters are well aware that the colours at the red end of thespectrum are apt to appear as advancing, while those of the violet endare known as retiring. The appearance of relief given by a gildedpattern on a dark blue as ground, is in part referable to the principlejust referred to. In addition, it appears to involve a difference in theaction of the muscles of accommodation in the successive adaptations ofthe eye to the most refrangible and the least refrangible rays. (SeeBrücke, _Die Physiologie der Farben_, sec. 17. ) [39] Helmholtz tells us (_Populäre wissenschaftliche Vorträge_, 3tesHeft, p. 64) that even in a stereoscopic arrangement the presence of awrong cast shadow sufficed to disturb the illusion. [40] Among the means of giving a vivid sense of depth to a picture, emphasized by Helmholtz, is diminishing magnitude. It is obvious thatthe perceptions of real magnitude and distance are mutually involved. When, for example, a picture represents a receding series of objects, asanimals, trees, or buildings, the sense of the third dimension, isrendered much more clear. [41] A striking example of this was given in a painting, by Andsell, ofa sportsman in the act of shooting, exhibited in the Royal Academy in1879. [42] This is at least true of all near objects. [43] Helmholtz remarks _(op. Cit. _, p. 628) that the difficulty ofseeing the convex cast as concave is probably due to the presence of thecast shadow. This has, no doubt, some effect: yet the considerationurged in the text appears to me to be the most important one. [44] _Populäre wissenschaftliche Vorträge_, 3tes Heft, pp. 71, 72. [45] See, on this point, some excellent remarks by G. H. Lewes, _Problemsof Life and Mind_, third series, vol. Ii. P. 275. [46] To some extent this applies to the changes of apparent magnitudedue to altered position. Thus, we do not attend to the reduction of theheight of a small object which we are wont to handle, when it is placedfar below the level of the eye. And hence the error people make injudging of the point in the wall or skirting which a hat will reach whenplaced on the ground. [47] I refer to the experiments made by Exner, Wundt, and others, indetermining the time elapsing between the giving of a signal to a personand the execution of a movement in response. "It is found, " says Wundt, "by these experiments that the exact moment at which a sense-impressionis perceived depends on the amount of preparatory self-accommodation ofattention. " (See Wundt, _Physiologische Psychologie_, ch. Xix. , especially p. 735. _et seq. _) [48] Quoted by Helmholtz, _op. Cit. _, p. 626. [49] When the drawing, by its adherence to the laws of perspective, doesnot powerfully determine the eye to see it in one way rather than in theother (as in Figs. 5 to 7), the disposition to see the one form ratherthan the other points to differences in the frequency of the originalforms in our daily experience. At the same time, it is to be observedthat, after looking at the drawing for a time under each aspect, thesuggestion now of the one and now of the other forces itself on the mindin a curious and unaccountable way. [50] _Ueber die phantastischen Gesichsterscheinungen_, p. 45. [51] Another side of histrionic illusion, the reading of the imitatedfeelings into the actors' minds, will be dealt with in a later chapter. [52] In a finished painting of any size this preparation is hardlynecessary. In these cases, in spite of the great deviations from truthin pictorial representation already touched on, the amount of essentialagreement is so large and so powerful in its effect that even anintelligent animal will experience an illusion. Mr. Romanes sends me aninteresting account of a dog, that had never been accustomed topictures, having been put into a state of great excitement by theintroduction of a portrait into a room, on a level with his eye. It isnot at all improbable that the lower animals, even when sane, arefrequently the subjects of slight illusion. That animals dream is a factwhich is observed as long ago as the age of Lucretius. [53] This kind of illusion is probably facilitated by the fact that theeye is often performing slight movements without any clear consciousnessof them. See what was said about the limits of sensibility, p. 50. [54] _Mental Physiology_, fourth edit. , p. 158. [55] In persons of very lively imagination the mere representation of anobject or event may suffice to bring about such a semblance ofsensation. Thus, M. Taine (_op. Cit. _, vol. I. P. 94) vouches for theassertion that "one of the most exact and lucid of modern novelists, "when working out in his imagination the poisoning of one of hisfictitious characters, had so vivid a gustatory sensation of arsenicthat he was attacked by a violent fit of indigestion. [56] Mentioned by Dr. Carpenter (_Mental Physiology_, p. 207), whereother curious examples are to be found. [57] See _Annales Médico-Psychologiques_, tom. Vi. P. 168, etc. ; tom. Vii. P. 1. Etc. [58] I have already touched on the resonance of a sense-impression whenthe stimulus has ceased to act (see p. 55). The remarks in the text holdgood of all such after-impressions, in so far as they take the form offully developed percepts. A good example is the recurrence of the imagesof microscopic preparations, to which the anatomist is liable. (SeeLewes, _Problems of Life and Mind_, third series, vol. Ii. P. 299. )Since a complete hallucination is supposed to involve the peripheralregions of the nerve, the mere fact of shutting the eye would not, it isclear, serve as a test of the origin of the illusion. [59] That subjective sensation may become the starting-point in completehallucination is shown in a curious instance given by Lazarus, andquoted by Taine, _op. Cit. _, vol. I. P. 122, _et seq. _ The Germanpsychologist relates that, on one occasion in Switzerland, after gazingfor some time on a chain of snow-peaks, he saw an apparition of anabsent friend, looking like a corpse. He goes on to explain that thisphantom was the product of an image of recollection which somehowmanaged to combine itself with the (positive) after-image left by theimpression of the snow-surface. [60] For an account of Mr. Galton's researches, see _Mind_, No. Xix. Compare, however, Professor Bain's judicious observations on theseresults in the next number of _Mind_. The liability of children to takeimages for percepts, is illustrated by the experiences related in acurious little work, _Visions_, by E. H. Clarke, M. D. (Boston, U. S. , 1878), pp. 17, 46, and 212. [61] A common way of describing the relation of the hallucinatory toreal objects, is to say that the former appear partly to cover and hidethe latter. [62] Griesinger remarks that the forms of the hallucinations of theinsane rarely depend on sense-disturbances alone. Though these are oftenthe starting-point, it is the whole mental complexion of the time whichgives the direction to the imagination. The common experience of seeingrats and mice running about during a fit of _delirium tremens_ very wellillustrates the co-operation of peripheral impressions not usuallyattended to, and possibly magnified by the morbid state of sensibilityof the time (in this case flying spots, _muscæ volitantes_), withemotional conditions. (See Griesinger, _loc. Cit. _, p. 96. ) [63] Wundt (_Physiologische Psychologie_, p. 652) tells us of an insanewoodman who saw logs of wood on all hands in front of the real objects. [64] It is stated by Baillarger (Mémoires de l'Académie Royale deMédicine, tom. Xii. P. 273, etc. ) that while visual hallucinations aremore frequent than auditory in healthy life, the reverse relation holdsin disease. At the same time, Griesinger remarks (_loc. Cit. _, p. 98)that visual hallucinations are rather more common than auditory indisease also. This is what we should expect from the number ofsubjective sensations connected with the peripheral organ of vision. Thegreater relative frequency of auditory hallucinations in disease, ifmade out, would seem to depend on the close connection betweenarticulate sounds and the higher centres of intelligence, which centresare naturally the first to be thrown out of working order. It ispossible, moreover, that auditory hallucinations are quite as common asvisual in states of comparative health, though more easily overlooked. Professor Huxley relates that he is liable to auditory though not tovisual hallucinations. (See _Elementary Lessons in Physiology_, p. 267. ) [65] See Baillarger, _Mémoires de l'Académie Royale de Médicine_, tom. Xii. P. 273, _et seq. _ [66] See Baillarger, _Annales Médico-Psychologiques_, tom. Vi. P. 168_et seq. _; also tom. Xii. P. 273, _et seq. _ Compare Griesinger, _op. Cit. _ In a curious work entitled _Du Démon de Socrate_ (Paris, 1856), M. Lélut seeks to prove that the philosopher's admonitory voice was anincipient auditory hallucination symptomic of a nascent stage of mentalalienation. [67] This is well brought out by Dr. J. Hughlings Jackson, in the papersin _Brain_, already referred to. [68] _Friend_, vol. I. P. 248. The story is referred to by Sir W. Scottin his _Demonology and Witchcraft_. [69] See E. B. Tylor, _Primitive Culture_, ch. Xi. ; _cf. _ HerbertSpencer, _Principles of Sociology_, ch. X. [70] For a fuller account of the different modes ofdream-interpretation, see my article "Dream, " in the ninth edition ofthe _Encyclopædia Britannica_. [71] For a fuller account of the reaction of dreams on wakingconsciousness, see Paul Radestock, _Schlaf und Traum_. The subject istouched on later, under the Illusions of Memory. [72] For an account of the latest physiological hypotheses as to theproximate cause of sleep, see Radestock, _op. Cit. _, appendix. [73] Plutarch, Locke, and others give instances of people who neverdreamt. Lessing asserted of himself that he never knew what it was todream. [74] The error touched on here will be fully dealt with under Illusionsof Memory. [75] For a very full, fair, and thoughtful discussion of this wholequestion, see Radestock, _op. Cit. _, ch. Iv. [76] This may be technically expressed by saying that the liminalintensity (Schwelle) is raised during sleep. [77] See Wundt, _Physiologische Psychologie_, pp. 188-191. [78] There is, indeed, sometimes an undertone of critical reflection, which is sufficient to produce a feeling of uncertainty andbewilderment, and in very rare cases to amount to a vague consciousnessthat the mental experience is a dream. [79] _Observations on Man_, Part I. Ch. Iii, sec. 5. [80] Quoted by Radestock, _op. Cit. _, p. 110. [81] _Le Sommeil et les Rêves_, p. 132, _et seq. _ [82] _Das Leben des Traumes_, p. 369. Other instances are related byBeattie and Abercrombie. [83] _Le Sommeil et les Rêves_, p. 42, _et seq. _ [84] _Beiträge sur Physiognosie und Heautognosie_, p. 256. For othercases see H. Meyer, _Physiologie der Nervenfaser_, p. 309; andStrümpell, _Die Natur und Entstehung der Träume_, p. 125. [85] A very clear and full account of these organic sensations, orcommon sensations, has recently appeared from the pen of A. Horwicz inthe _Vierteljahrsschrift für wissenschaftliche Philosophie_, iv. Jahrgang 3tes Heft. [86] Schopenhauer uses this hypothesis in order to account for theapparent reality of dream-illusions. He thinks these internal sensationsmay be transformed by the "intuitive function" of the brain (by means ofthe "forms" of space, time, etc. ) into quasi-realities, just as well asthe subjective sensations of light, sound, etc. , which arise in theorgans of sense in the absence of external stimuli. (See _Versuch überdas Geisterschen: Werke_, vol. V. P. 244, _et seq. _) [87] _Das Alpdrücken_, pp. 8, 9, 27. [88] It is this fact which justifies writers in assigning a prognosticcharacter to dreams. [89] A part of the apparent exaggeration in our dream-experiences may beretrospective, and due to the effect of the impression of wonder whichthey leave behind them. (See Strümpell, _Die Natur und Entstehung derTräume_. ) [90] _Cf. _ Radestock, _op. Cit. _, pp. 131, 132. [91] I was on one occasion able to observe this process going on in thetransition from waking to sleeping. I partly fell asleep when sufferingfrom toothache. Instantly the successive throbs of pain transformedthemselves into a sequence of visible movements, which I can onlyvaguely describe as the forward strides of some menacing adversary. [92] Even the "unconscious impressions" of waking hours, that is to say, those impressions which are so fugitive as to leave no psychical tracebehind, may thus rise into the clear light of consciousness duringsleep. Maury relates a curious dream of his own, in which there appeareda figure that seemed quite strange to him, though he afterwards foundthat he must have been in the habit of meeting the original in a streetthrough which he was accustomed to walk (_loc. Cit. _, p. 124). [93] See p. 53. [94] See Maury, _loc. Cit. _, p. 146. [95] See what was said respecting the influence of a dominant emotionalagitation on the interpretation of actual sense-impressions. [96] It is proved experimentally that the ear has a much closer organicconnection with the vocal organ than the eye has. Donders found that theperiod required for responding vocally to a sound-signal is less thanthat required for responding in the same way to a light-signal. [97] On the nature of this impulse, as illustrated in waking and insleep, see the article by Delboeuf, "Le Sommeil et les Rêves, " inthe _Revue Philosophique_, June, 1880, p. 636. [98] _Physiologische Psychologie_, p. 660. [99] I may, perhaps, observe, after giving two dreams which have to dowith mathematical operations, that, though I was very fond of them in mycollege days, I have long ceased to occupy myself with these processes. I would add, by way of redeeming my dream-intelligence from a deservedcharge of silliness, that I once performed a respectable intellectualfeat when asleep. I put together the riddle, "What might a wooden shipsay when her side was stove in? Tremendous!" (Tree-mend-us). I was awareof having tried to improve on the form of this pun. I am happy to say Iam not given to punning during waking life, though I had a fit of itonce. It strikes me that punning, consisting as it does essentially ofoverlooking sense and attending to sound, is just such a debased kind ofintellectual activity as one might look for in sleep. [100] See Radestock, _op. Cit. _, ch. Ix. ; _Vergleichung des Traumes mitdem Wahnsinn_. [101] For Spinoza's experience, given in his own words, see Mr. F. Pollock's _Spinoza_, p. 57; _cf. _ what Wundt says on his experience, _Physiologische Psychologie_, p. 648, footnote 2. [102] See an interesting account of "Recent Researches on Hypnotism, " byG. Stanley Hall, in _Mind_, January, 1881. [103] I need hardly observe that physiology shows that there is noseparation of different elementary colour-sensations which are locallyidentical. [104] This kind of error is, of course, common to all kinds ofcognition, in so far as they involve comparison. Thus, the presence ofthe excitement of the emotion of wonder at the sight of an unusuallylarge object, say a mountain, disposes the mind to look on it as thelargest of its class. Such illusions come midway between presentativeand representative illusions. They might, perhaps, be specially markedoff as illusions of "judgment. " [105] So far as any mental state, though originating in a fusion ofelements, is now unanalyzable by the best effort of attention, we mustof course regard it in its present form as simple. This distinctionbetween what is simple or complex in its present nature, and what isoriginally so, is sometimes overlooked by psychologists. Whether thefeelings and ideas here referred to are now simple or complex, cannot, Ithink, yet be very certainly determined. To take the idea of space, Ifind that after practice I recognize the ingredient of muscular feelingmuch better than I did at first. And this exactly answers to Helmholtz'scontention that elementary sensations as partial tones can be detectedafter practice. Such separate recognition may be said to depend oncorrect representation. On the other hand, it must be allowed that thereis room for the intuitionist to say that the associationist is herereading something into the idea which does not belong to it. It is to beadded that the illusion which the associationist commonly seeks tofasten on his opponent is that of confusing final with originalsimplicity. Thus, he says that, though the idea of space may now to allintents and purposes be simple, it was really built up out of manydistinct elements. More will be said on the relation of questions ofnature and genesis further on. [106] I may as well be frank and say that I myself, assuming free-willto be an illusion, have tried to trace the various threads of influencewhich have contributed to its remarkable vitality. (See _Sensation andIntuition_, ch. V. , "The Genesis of the Free-Will Doctrine. ") [107] I purposely leave aside here the philosophical question, whetherthe knowledge of others' feelings is intuitive in the sense of beingaltogether independent of experience, and the manifestation of afundamental belief. The inherited power referred to in the text might, of course, be viewed as a transmitted result of ancestral experience. [108] I here assume, along with G. H. Lewes and other competent dramaticcritics, that the actor does not and dares not feel what he expresses, at least not in the perfectly spontaneous way, and in the same measurein which he appears to feel it. [109] The illusory nature of much of this emotional interpretation ofmusic has been ably exposed by Mr. Gurney. (See _The Power of Sound_, p. 345, _et seq. _) [110] The reader will note that this impulse is complementary to theother impulse to view all mental states as analogous to impressionsproduced by external things, on which I touched in the last chapter. [111] Errors of memory have sometimes been called "fallacies, " as, forexample, by Dr. Carpenter (_Human Physiology_, ch. X. ). While preferringthe term "illusion, " I would not forget to acknowledge my indebtednessto Dr. Carpenter, who first set me seriously to consider the subject ofmnemonic error. [112] From this it would appear to follow that, so far as a percept isrepresentative, recollection must be re-representative. [113] The relation of memory to recognition is very well discussed by M. Delboeuf, in connection with a definition of memory given byDescartes. (See the article "Le Sommeil et les Rêves, " in the _RevuePhilosophique_, April, 1880, p. 428, _et seq. _) [114] A very interesting account of the most recent physiological theoryof memory is to be found in a series of articles, bearing the title, "LaMémoire comme fait biologique, " published in the _Revue Philosophique_, from the pen of the editor, M. Th. Ribot. (See especially the _Revue_ ofMay, 1880, pp. 516, _et seq. _) M. Ribot speaks of the modification ofparticular nerve-elements as "the static base" of memory, and of theformation of nerve-connections by means of which the modified elementmay be re-excited to activity as "the dynamic base of memory" (p. 535). [115] What constitutes the difference between such a progressive and aretrogressive movement is a point that will be considered by-and-by. [116] It is not easy to say how far exceptional conditions may serve toreinstate the seemingly forgotten past. Yet the experiences of dreamersand of those who have been recalled to consciousness after partialdrowning, whatever they may prove with respect to the revivability ofremote experiences, do not lead us to imagine that the range of ourdefinitely localizing memory is a wide one. [117] _Der Zeitsinn nach Versuchen_, p. 36, _et seq. _ [118] _Physiologische Psychologie_, p. 782. [119] Wundt refers these errors to variations in the state ofpreadjustment of the attention to impressions and representations, according as they succeed one another slowly or rapidly. There is littledoubt that the effects of the state of tension of the apparatus ofattention, are involved here, though I am disposed to think that Wundtmakes too much of this circumstance. (See _Physiologische Psychologie_, pp. 782, 783. I have given a fuller account of Wundt's theory in _Mind_, No. I. ) [120] Strictly speaking, it would occupy more time, since the effort ofrecalling each successive link in the chain would involve a greaterinterval between any two images than that between the correspondingexperiences. [121] I need hardly say that there is no sharp distinction between thesetwo modes of subjective appreciation. Our estimate of an interval as itpasses is really made up of a number of renewed anticipations andrecollections of the successive experiences. Yet we can say broadly thatthis is a prospective estimate, while that which is formed when theperiod has quite expired must be altogether retrospective. [122] See an interesting paper on "Consciousness of Time, " by Mr. G. J. Romanes, in _Mind_ (July, 1878). [123] It is well known that there is, from the first, a gradual fallingoff in the strength of a sensation of light when a moderately brightobject is looked at. [124] _Cf. _ Hartley, _Observations on Man_, Part I. Ch. Iii. Sec. 4(fifth edit. , p. 391). [125] See Dr. Carpenter's _Mental Physiology_, fourth edit, p. 456. [126] This is, perhaps, what is meant by saying that people recall theirpast enjoyments more readily than their sufferings. Yet much seems toturn on temperament and emotional peculiarities. (For a fullerdiscussion of the point, see my _Pessimism_, p. 344. ) [127] The only exception to this that I can think of is to be found inthe power which I, at least, possess, after looking at a new object, ofrepresenting it as a familiar one. Yet this may be explained by sayingthat in the case of every object which is clearly apprehended there mustbe vague revivals of _similar_ objects perceived before. Oases in whichrecent experiences tend, owing to their peculiar nature, very rapidly toassume the appearance of old events, will be considered presently. [128] _Mental Physiology_, p. 456. [129] _Mental Physiology_, second edit. , p. 172. [130] _Loc. Cit. _, p. 390. [131] This source of error has not escaped the notice of autobiographersthemselves. See the remarks of Goethe in the opening passages of his_Wahrheit und Dichtung_. [132] One wonders whether those persons who, in consequence of an injuryto their brain, periodically pass from a normal into an abnormalcondition of mind, in each of which there is little or no memory of thecontents of the other state, complete their idea of personal continuityin each state by the same kind of process as that described in the text. [133] The reader will remark that this condition of clear intellectualconsciousness, namely, a certain degree of similarity and continuity ofcharacter in our successive mental states, is complementary to the othercondition, constant change, already referred to. It may, perhaps, besaid that all clear consciousness lies between two extremes of excessivesameness and excessive difference. [134] It follows that any great transformation of our environment maylead to a partial confusion with respect to self. For not only do greatand violent changes in our surroundings beget profound changes in ourfeelings and ideas, but since the idea of self is under one of itsaspects essentially that of a relation to not-self, any great revolutionin the one term, will confuse the recognition of the other. This fact isexpressed in the common expression that we "lose ourselves" when inunfamiliar surroundings, and the process of orientation, or "taking ourbearings, " fails. [135] On these disturbances of memory and self-recognition in insanity, see Griesinger, _op. Cit. _, pp. 49-51; also Ribot, "Des DésordresGénéraux de la Mémoire, " in the _Revue Philosophique_, August, 1880. Itis related by Leuret (_Fragments Psych. Sur la Folie_, p. 277) that apatient spoke of his former self as "la personne de moi-même. " [136] In the following account of the process of belief and its errors, I am going over some of the ground traversed by my essay on _Belief, itsVarieties and Conditions_ ("Sensation and Intuition, " ch. Iv. ). To thisessay I must refer the reader for a fuller analysis of the subject. [137] For an account of the difference of mechanism in memory andexpectation, see Taine, _De l'Intelligence_, 2ième partie, livrepremier, ch. Ii. Sec. 6. [138] J. S. Mill distinguishes expectation as a radically distinct modeof belief from memory, but does not bring out the contrast with respectto activity here emphasized (James Mill's _Analysis of the Human Mind_, edited by J. S. Mill, p. 411, etc. ). For a fuller statement of my view ofthe relation of belief to action, as compared with that of ProfessorBain, see my earlier work. [139] For some good remarks on the logical aspects of future events asmatters of fact, see Mr. Venn's _Logic of Chance_, ch. X. [140] James Mill's _Analysis of the Human Mind_, edited by J. S. Mill, vol. I p. 414, _et seq. _ [141] _Principles of Geology_, ch. Iii. [142] To make this rough analysis more complete, I ought, perhaps, toinclude the effect of all the errors of introspection, memory, andspontaneous belief, into which the person himself falls, in so far asthey communicate themselves to others. [143] In the case of a vain woman thinking herself much more pretty thanothers think her, the error is still more obviously one connected with abelief in objective fact. [144] _The Study of Sociology_, ch. Ix. [145] As a matter of fact, the proportion of accurate knowledge to erroris far larger in the case of classes than of individuals. Propositionswith general terms for subject are less liable to be faulty thanpropositions with singular terms for subject. [146] For a description of each of these extremes of boundless gaietyand utter despondency, see Griesinger, _op. Cit. _, Bk. III. Ch. I. Andii. The relation of pessimism to pathological conditions is familiarenough; less familiar is the relation of unrestrained optimism. YetGriesinger writes that among the insane "boundless hilarity, " with "afeeling of good fortune, " and a general contentment with everything, isas frequent as depression and repining (see especially p. 281, also pp. 64, 65). [147] It has been seen that, from a purely psychological point of view, even what looks at first like pure presentative cognition, as, forexample, the recognition of a present feeling of the mind, involves aningredient of representation. [148] See especially what was said about the _rationale_ of illusions ofperception, pp. 37, 38. [149] I say "usually, " because, as we have seen, there may sometimes bea permanent and even an inherited predisposition to active illusion inthe individual temperament and nervous organization. [150] See what was said on the nature of passive illusions of sense (pp. 44, 68, 70, etc. ) The logical character of illusion might be brought outby saying that it resembles the fallacy which is due to reasoning froman approximate generalization as though it were a universal truth. Inthus identifying illusion and fallacy, I must not be understood to saythat there is, strictly speaking, any such thing as an unconsciousreasoning process. On the contrary, I hold that it is a contradiction totalk of any _mental_ operation as altogether unconscious. I simply wishto show that, by a kind of fiction, illusion may be described as theresult of a series of steps which, if separately unfolded toconsciousness (as they no longer are), would correspond to those of aprocess of inference. The fact that illusion arises by a process ofcontraction out of conscious inference seems to justify this use oflanguage, even apart from the fact that the nervous processes in the twocases are pretty certainly the same. [151] If we turn from the region of physical to that of moral ideas, wesee this historical collision between common and individual convictionin a yet more impressive form. The teacher of a new moral truth hasagain and again been set down to be an illusionist by a society whichwas itself under the sway of a long-reigning error. As George Eliotobserves, "What we call illusions are often, in truth, a wider vision ofpast and present realities--a willing movement of a man's soul with thelarger sweep of the world's forces. " [152] To make this account of the philosophic problem of theobject-world complete, I ought to touch not only on the distinctionbetween the vulgar and the scientific view of material things, but alsoon the distinction, within physical science, between the less and themore abstract view roughly represented by molar and molecular physics. [153] For an excellent account of the distinction between the scientificand the philosophic point of view, see Mr. Shadworth Hodgson's_Philosophy of Reflection_, Bk. I. Chs. I. And iii. ; also Bk. III. Chs. Vii. And viii. [154] I hold, in spite of Berkeley's endeavours to reconcile hisposition with that of common sense, that the popular view does at leasttend in this direction. That is to say, the every-day habit, whenconsidering the external world, of abstracting from particular minds, leads on insensibly to that complete detachment of it from mind ingeneral which expresses itself in the first stage of philosophicreflection, crude realism. The physicist appears to me, both from thefirst essays in Greek "nature-philosophy, " as also from the notinfrequent confusion even to-day between a perfectly safe "scientificmaterialism" and a highly questionable philosophic materialism, to sharein this tendency to take separate consideration for separate existence. Each new stage of abstraction in physical science gives birth to a newattempt to find an independent reality, a thing-in-itself, hiddenfurther away from sense. [155] See the interesting autobiographical record of the growth ofphilosophic doubt in the _Première Méditation_ of Descartes. [156] The appeal is not, as we have seen, invariably from sight totouch, but may be in the reverse direction, as in the recognition of theduality of the points of a pair of compasses, which seem one to thetactual sense. [157] I might further remark that this "collective experience" includespreviously detected illusions of ourselves and of others. [158] M. Taine frankly teaches that what is commonly called accurateperception is a "true hallucination" (_De l'Intelligence_, 2ième partie, Livre I. Ch. I. Sec. 3). [159] It only seems to do so, apart from philosophic assumptions, incertain cases where experience testifies to a uniform untrustworthinessof the origin. For example, we may, on grounds of matter of fact andexperience, be disposed to distrust any belief that we recognize asspringing from an emotional source, from the mind's feelings and wishes. I may add that a so-called intuitive belief may refer to a matter offact which can be tested by the facts of experience and by scientificmethods. Thus, for example, the old and now exploded form of thedoctrine of innate ideas, which declared that children were born withcertain ideas ready made, might be tested by observation of childhood, and reasoning from its general intellectual condition. The same appliesto the physiological theories of space-perception, supposed to be basedon Kant's doctrine, put forward in Germany by Johannes Müller and the"nativistic school. " (See my exposition and criticism of these doctrinesin _Mind_, April, 1878, pp. 168-178 and 193-195. )