The Relations of Mind and Brain

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Preface To Third Edition

For the present Edition the discussion on “Animal Intelligence ” has been carefully revised. The closing part of the chapter on this subject has been entirely re-written. Deliberate account has been made of the most recent observations, including those on the ‘Language of Animals,” and the discussion on ‘‘Animal Ethics” in the treatise on “Justice” by Mr. Herbert Spencer.

Extended observations on Hypnotism have thrown additional light on the relations of Mind to bodily sensibility and movement. On this account I have been led to inquire how far fresh inductions have become possible from the great array of facts supplied by enlarged medical experience. High value attaches to what has been lately done by the School of Nancy, and by other observers, specially in Paris and in Berlin, assigning a prominent place to “Suggesticn,”

in causation of nerve-sleep, as well as subsequently in vi PREFACE TO THE THIRD EDITION.

direction of the sleeper’s activity. The subject seems one of so much importance, theoretically and practically, that I have added an Appendix to the present edition, giving a full discussion of the nature of the Hypnotic sleep, and of the testimony regarding the relations of mind to body afforded by Hypnotic phenomena. The data have been so carefully verified as to be now widely acknowledged by scientific observers, including many medical practitioners.

Hee

UNIVERSITY OF EDINBURGH, January 13, 1892.

Preface To The Second Edition

THE demand for a second edition came so much earlier than had been expected, that it found me unprepared to meet it. For the delay which has thus occurred in publication I have now to express regret.

The work could not, I was persuaded, be regarded * as complete, without a thorough study of “ Animai Intelligence ;” whereas continued research and reflection had greatly deepened my sense of the perplexities of the subject.

Gradually I became satisfied that our studies in Neurology were being to some extent misdirected by too exclusive attention to comparative Brain structure. This led on to the conclusion, now emphasised in this edition, that the primary requisite for successful research is to compare the entire Nerve System of the several animals, and not merely the Brain, or even the combination of Nerve Centres, belonging wath PREFACE TO THE SECOND EDITION.

to them. As the Sensory System (aided always in functional activity by the Motor) is the recognised instrument of discrimination, it naturally follows that comparative development of Sensory Apparatus must be taken as a leading feature along with Cerebral development. From this position a considerable number of existing perplexities are seen to be modified in a marked degree. The intelligence of the ant, the dog, the horse, and the ape, is presented in a different light; and the results are such as appear to call for some modification of the Theory of Evolution, in so far as it is concerned with the relation of evolution of Organism to evolution of Intelligence. Without venturing to claim that a complete theory of ‘“‘ Animal Intelligence” has been here worked out, I submit the outlines of a theory which appears to me to come nearer a true induction than comparative neurology has hitherto reached.

Besides the addition of the new chapter on “ Animal Intelligence,” consideration has been given to recent research and. discussion in other branches of the subject; and, besides this, the many valuable criticisms of the first edition of this work which had appeared in scientific journals have been carefully pondered.

I have to express my sense of the kindness shown by recognised authorities in Neurology, when noticing

PREFACE TO THE SECOND EDITION. ix a first venture into a most difficult region of research by one whose main studies have been devoted to the very different region of Mental Philosophy.

By my colleagues connected with the Medical Faculty I have been laid under fresh obligations. To Professor Turner, LL.D., I have been largely indebted, and also to Professor J. Cossar Ewart, M.D., since he entered on the duties of the Chair of Natural History. The drawings supplied by Professor Ewart of the antenna and leg of the ant are a valuable contribution to the work, and will, with other figures introduced into this edition, afford important help towards estimating the argument now submitted.

H. C.

UNIVERSITY OF EDINBURGH, November 10, 1883.

Preface To The First Edition

THE object of the present work is to ascertain what theory of mental life is warranted on strictly scientific evidence. a.

The order followed is to consider, first, the latest results of anatomical and physiological research as to _the structure and functions of the brain; second, the facts in human life unaccounted for by anatomical and physiological science, and requiring to be assigned to a higher nature.

On the side of Mental Philosophy, it must be recognised that analysis of consciousness cannot be regarded as affording a complete survey of the facts of personal life. On the other hand, it is clear that the known facts connected with cerebral action do not include familiar phases of mental activity. If we allow ourselves to be engrossed with Physioxil PREFACE TO THE FIRST EDITION.

logical investigations as to brain, we restrict our attention to a single class of facts, and become unable to take a view of human life as a totality. The whole range of evidence must be traversed, if we are to secure a harmonious representation of the constitution of human nature.

The acknowledgments I have to make for friendly assistance during the long-continued and difficult investigations involved are many. Great generosity on the part of my colleagues has given me full advantage of the facilities for imquiry which the University affords. I have to record my special gratitude to Professor Turner, of the Chair of Anatomy, who has been untiring in his friendly assistance ; to Professor Rutherford, of the Chair of Physiology ; to Professor Crum Brown, of the Chair of Chemistry ; to Professor Grainger Stewart, of the Chair of Practice of Medicine; and to Dr. Clouston, Lecturer on Mental Diseases in the University.

I have also to express my particular thanks to Dr. James A. Sidey foi revision of the proof-sheets, and to the Rev. Alexander Mair, D.D., for revision of selected portions of the work. Valuable aid has also been afforded me by Dr. Dodds, Assistant to the Professor of Physiology ; and by Mr. Stirling, Assistant

PREFACE TO THE FIRST EDITION. ’ ili to the Professor of Anatomy, and Assistant Curator of the Anatomical Museum.

Readers will understand that no one of the friends named is in the least degree committed to the positions here maintained.

Thanks are also due to many authors and friends who have kindly replied to inquiries addressed to them. 7

Large use of Illustrations prepared for standard works in Anatomy and Physiology has been generously afforded me. Acknowledgment of these favours is made as the illustrations are introduced.

He:

UNIVERSITY OF EDINBURGH, 26th April 1879.

Chapter I. Relations Of Philosophy And Science

Page Physical Science and Mental Philosophy constitute a unity—The problem of Existence is one, and must be interpreted by reference to the nature of man as rational—Physiology and Psychology constitute together the science of human life ; scientific methods belong to both; Psychology as truly as Physiology springs from observation— Dependence on consciousness is not peculiar to the mental philosopher—A charge of untrustworthiness cannot be substantiated against self-consciousness—Experience of the imsane presents the only debatable points, yet the physician trusts the consciousness of his patient—Introspection is a necessary process for observation, but is not sufficient for a philosophy of our nature—Physiology is not yet sufficiently advanced to explain the action of nerve and brain—There remains as an

essential question, how to account for “ mental phenomena,” . 1-9

Chapter II. Structure Of The Brain

Three membranes which afford covering for the brain ; appearance of the brain; its growth and increase in weight during early life; ordinary weight of European brain—Configuration and structure of the brain—Side view of the organ ; convolutions ; fissures ; subdivisions of the hemisphere—Upper view of the brain, showing distinction of the two hemispheres—Diversity of convolutions in the two hemispheres—Basis of comparison of different brains; mass and weight; quality; proportion between brain and body—Greater weight of brain in man than in woman - —Minimum weight of normal brain-—Examples of heavy brain— Jaternal structure of the brain; the grey matter and the white ;

b xvi CONTENTS.

PAGE nerve cells packed in neuroglia ; nerve fibres ; structure of fibre ; chemical composition—Union of the hemispheres—Massing of the sensory and motor nerves—Basal ganglia ; lower surface ; subordinate parts of the nerve centre—Supply of blood for the brain, ‘ ; ‘ .

Chapter III. . 10-38

THE NERVE SYSTEM AS DEPENDENT ON THE GREAT NERVE CENTRE.

The nerve system ; nerves of special sense ; spinal marrow ; distribution of fibres ; efferent and afferent—The sympathetic system of nerves—Sensory and motor nerves have their common meetingplace in the brain—Stores of nerve energy, how acted upon ; molecular changes consequent on activity—The grey matter not sensitive under touch or injury—Facility of action of nerve fibres acquired by frequent use—Relation established between * distinct nerve lines—Ratio of intensity in sensation—Nerves of special sense; smell ; sight; hearing, , . 4 F . 39-

Chapter IV. Localisation Of Functions In Distinct Portions Of The Brain

Inquiry as to the possibility of localising distinct functions in certain parts of the brain— Electric excitation of the brain— Experiments of Fritsch and Hitzig—Experiments of Dr. Ferrier, illustrated by identification of sensory and motor centres in the brain of the monkey—Analogous results with the brain of the dog— Interpretation of the facts ; twofold classification of the centres ; tests of accuracy; perplexity as to ‘‘silent portions,” over which excitation has proved impossible, C < ; =» WO-122,

Chapter V

COMPARISON OF THE STRUCTURE AND FUNCTIONS OF BRAIN IN LOWER AND HIGHER FORMS OF ANIMAL LIFE.

Comparative structure of brain in different animals—Homology of brain—Primary arrangement of nerve system—Brain of carp, frog, pigeon, rat, rabbit, cat, dog, horse, monkey, man-like ape, man; points of resemblance and difference between the two last named—Brain of the elephant and of the whale, 2 123-186

CONTENTS. Xvii

Chapter VI. Results Of Anatomical And Physiological Investigations

: PAGE Results of anatomical and physiological investigations—Common characteristics of the nerve system, and of the nerve centre— Increasing complexity of nerve system as we ascend the scale of animal life—Distinction of sensory and motor apparatus in all cases—Activity of sensory apparatus; impulse; relation of peripheral organ to the nerve cell; action of corpuscle or other terminal organ ; action of the correlated nerve cells; consequent experience — Motor apparatus; impulse ; evolution of nerve energy ; transmission; consequent muscular activity ; joint action of muscles—Ganglionic masses—In all known organism,

Brain is the chief organ of sensori-motor activity, . : 187-197

Chapter VII. Animal Intelligence

Summary of our knowledge of Brain Structure,—Summary of our knowledge of Brain Functions—Discrimination and Purposive Action possible without Intelligence—The Sensory System must be the Avenue for explanation of appearances of Intelligence in Animals—Radical distinction between neural phenomena and mental phenomena—Animals credited with high intelligence are distinguished by special sensibility—Tur Ant,—its intelligence, its brain, its sensory system, the antennae; contrast of its intelligence with that of the dog—Tur CuricK,—Stages of development of the head, prominence of the eye, use of vision ; shows knowledge of distance apart from training; use of hearing, knowledge of direction of sound ; difference between its use of special senses and the facts of human experience—Tur Doe (including references to the Horse), large provision for use of Smell ; this sense the guide to food, and direction in travelling ; action of sight; increased sensory apparatus related with increased complexity of brain; intelligence dependent on companionship with man; effects of training,—restraint,—inducement ;—The Scotch Collie ;—Poverty of intellect in the dog; popular estimate of the animal ;—the place of the dog’s intelligence under a Theory of Evolution—Tuz Monkey and Apz,-— comparative brain development—absence of speciality in sensory apparatus—recorded observations as to intelligence—severance from man—THE ELEPHANT and WHALE,—muscular power and swiftness of movement as related to brain structure—Brain structure as related to Intelligence—Evolution as concerned with

CONTENTS.

xVill PAGE Differences in brain structure—‘‘ Mind Cells”—‘‘ Animal Language”—Training of the Dog—Perceptive Intelligence, and Rational Intelligence, . é ¢ ; 6 5 6 198-288

Chapter VIII. Personal Experience As Connected With Action Of The Sensory System

Sensory apparatus needful for consciousness of sensation—Relations of Nerve Centres—Two distinct sets of facts in human experience —tThey are not two sides of the same thing—The action of sensory apparatus does not include action of Intelligence—Intelligence interprets our sensations—Our Thoughts are not caused as our sensations are—Diversity in size and form of nerve cells does not account for exercise of Intelligence—Diverse forms of cells illustrated—Functions of Intelligence cannot be assigned to giant pyramidal cells—Touch and Sensation—Succession of sensations —Comparison of sensations— Knowledge of objects through sensation— Intelligence of man entirely distinct from sensory apparatus— Organic elements in sensory experience—Non-organic elements connected with sensory experience—Brain not the organ of Mind in the same sense as it is the organ of sensori-motor activity—The manner in which Mind maintains its relation with the Nerve System— Mind as self-directing Intelligence, . 289-317

Chapter IX. Experience As Connected With Motor Activity. ~

Relation between sensory and motor system—Reflex action—Sensori. motor activity, attended with consciousness—Voluntary motor activity— Voluntary restraint over nerves of sensibility—intelligent use of motor activity ; acquisition of skill in handicraft— Activity superior to the action and reaction of nerve tissue— Reflection and personal determination as connected with such activity—Knowledge of a power superior to motor activity— Intelligent self-control—Impossibility of accounting for the activity of such power by reference to the functions of brain, 318-345

Chapter X. Retentiveness Of Acquisition—memory

Memory—Double aspect of retentiveness—Physical acquisition, resulting in physical aptitudes—Memory proper as distinguished

CONTENTS. xix

PAGE from physical retentiveness—Difficulty and facility in retaining knowledge—Both illustrate intellectual action as a phase of voluntary control—Distinction and comparison involved in the recollection of knowledge—Difference between retentiveness and reproduction—Laws of association, the intellectual and the voluntary elements involved in their application—Theory suggesting that the facts known are recorded in the tissue of the brain— Its insufficiency to account for reproduction of knowledge, 346-368

Chapter XI. Use Of Speech

Use of speech—The mechanism of speech—Physical acquisition involved in use of speech—Articulate utterance is the expression of intelligent discrimination—Deaf-mutes, and the mode of their education—Case of Laura Bridgman—“ Lip-language”—Various phases of intellectual activity connected with the use of speech —Aphasia, or loss of speech ; examples illustrating the relation of voluntary intellectual action to speech, s ; q 369-396

Chapter XII. Action And Reaction Of Body And Mind

Action and reaction of Body and Mind—Influence of a disturbed bodily condition upon mind—Facts illustrative do not warrant the inference that mental activity is an organic process—Action of Mind upon Body—Rational control over bodily movements ; effect of deep emotion ; mental occupation modifying suffering ; mind aiding recovery from disease ; personal determination as it concerns endurance of toil or pain, . - : : a 397-409

Chapter XIII. Weariness, Sleep, And Unconsciousness

Weariness attendant on mental effort—Difference between mental work and brain work—The cause of weariness as the result of intellectual work—Phenomena of sleep—Dreaming— Phases of mental activity during sleep—Summary of conclusions as to mental action during sleep—Unconsciousness—Physical causes of it; mental explanation of its occurrence—Somnambulism— Trance—‘‘ Mesmeric Sleep,” . ; : : : : 410-445

Xx CONTENTS.

Chapter XIV.. Brain Disorders

PAGE Brain Disorders; misnamed “mental diseases””—Imperfect development of brain—Disease of brain; many forms of such disease ; mental experience consequent upon it—Illustrations of disordered cerebral condition with accompanying mental experience —Treatment of the insane, both physical and moral—Violent injury to the healthy brain, and the light thrown on mental activity by such injury—Personal conduct as producing or

averting insanity, . é : : . 3 4 é 446-494

Chapter XV. The Higher Forms Of Mental Activity

1. Man regarded as a thinker—The purely intellectual department of thought ; education ; scientific inquiry ; recent advances in science—2. Thought as concerned with the regulation of personal life—Moral law specially applicable to human life; the mode of its application—3. Thought as concerned with the Absolute Being, and His government of the universe— Religious beliefs existing among uncivilised tribes—Philosophie speculation concerning the origin of finite existence, . : ° 495-514

CHAPTER. XVEr

SUMMARY OF INTELLECTUAL RESULTS.

Summary of intellectual results—Personal experience as connected with nerve sensibility; and with motor activity—Voluntary intellectual exercise illustrated in connection with the laws of memory and the use of speech—Self-regulated life of man, as it is manifested in the process of reflection or reasoning, in the guidance of personal conduct under authority of moral law, and in the religious beliefs and rites of the various races of men— The nature of mind as indicated by its functions, ; 515-518

Hypnotism: Its nature, and its testimony as to the relations of Mind and Body, : A : 5 519-542

LIST OF ILLUSTRATIONS.

PAGE

Fie. 1. OureR CovERING OF BRAIN, . : 3 ; ; ll », 2. Posirion oF BRAIN IN THE CRANIUM, . é 5 5 9G .» 3. Ricur HemisPHERE oF Human Brat, - , | 14 . 4 Upper SURFACE, a : : : 3 So ly » 5. OurLIne or ConvoLuTions,—Ricut Sinz, , : a7 le “ral hit 5 ry UPPER SURFACE, s ; 18 <, 7. SECTION oF THE GREY MarTTeER, : ; : , we , 8. NERVE Frere, . ‘ ? : : ; os ,, 9. UNION oF THE HEMISPHERES, . : i atso ;, 10. APPEARANCE OF LOWER PORTION OF BRAIN, . é ‘ 31 », 11. Basat GANGLIA, = ‘ : F p M39 », 12. LowER SURFACE OF BRAIN, : . é be ot ,, 13. Lower Divisions or NERVE CENTRE, . : : 5 85 >, 14. Secrion oF THE SPINAL Corp, ; : : . 40 ;, 15. Touch CORPUSCLES (MAGNIFIED), 5 2 4 eee 4s ,, 16. SrRucTURE OF THE EYEBALL, . : : ; 5 », 17. STRUCTURE OF THE RETINA, . A ; A Os ,, 18. SecTION oF THE Ear, . ¢ , 5 ; a KD) ,, 19. INTERNAL ARRANGEMENTS OF THE Ear, ; : ee ,, 20., THE LABYRINTH OF THE Ear, . é : ‘ rie ,, 21. Upper SuRFACE OF BRAIN OF Doc, . : : gail ,, 22. BRAIN OF MONKEY, . : ? ; 3 . 84 i VES . A CENTRES OF STIMULATION, : A eS6 , 24. UPPER SURFACE, Re + : , ve Od ,, 25. Bratn or Doe, . ‘ , x ‘ F ae 99 na) DATE x5 Carp, A : 5 : 7 125 OH rf FRoG, A 3 ‘ é . ol ey eS: ns PIGEON, : . : 3 ; a lie

49,

LIST OF ILLUSTRATIONS.

. BRAIN oF Rat, 3 5 > RABBIT, ° : Pa Cat, e 5 Doe,

. InreRNAL Structure oF Doe’s BRAIN,

Brain oF Horss,

5 Monkey,

. Lert HemtsPHERE oF HUMAN BRAIN,

. Upper Vizw oF BRAIN oF CHIMPANZEE,

A Human Bratn,

. BRAIN OF ELEPHANT, .

5 WHALE,

. Motor AND SENSORY APPARATUS,

. NERVE System oF THE ANT,

. ANTENNA AND LEG oF THE ANT,

. OtFacrory TRACT IN THE Doa’s BRAIN, . OLFAcToKY Tract In Man’s BrRatn,

. BRAIN OF THE ORANG,

. ReLatep NERVE CENTRES IN HuMAN ORGANISM,

. APPEARANCE OF CELLS IN DIFFERENT LAYERS OF THE HuMAN

Brain,

DIAGRAM REPRESENTING COMMON EXPERIENCE OF MAN AND

ANIMAL, .

DIAGRAM REPRESENTING MAN’s GOVERNMENT OF DESIRES,

PAGE

505 506

THE RELATIONS OF MIND AND BRAIN.

Chapter I. Relations Of Philosophy And Science. ®

PHILOSOPHY and Science are so related as to constitute a unity. The one is concerned with the facts and problems of rational life ; the other with the facts and problems of material existence, animate and inanimate. They are at one in seeking a rational explanation of observed facts. They adopt the same method, depending upon observation, analysis, classification, and reasoning. However widely separated the regions of inquiry, searchers for truth are working in harmony, whether they recognise the fact or dispute it. Each group is a body of specialists, but the results of inquiry, wherever prosecuted, bear upon one grand problem concerning the universe. It is recognised equally by Philosophy and Science, that things existing constitute a system, or organised order of existence. It is granted, therefore, that careful research, whatever direction it take, must result in some contribution to the grand total of human knowledge. And it is equally clear that those most entitled to a hearing on any branch of inquiry are those who have devoted themselves to research in the department with which that inquiry is concerned. Only thus can real advance be made on the vast region of research which the universe presents. Philosophy must wait on Science, and Science in turn wait on Philosophy.

Here, as most readily occurs to one devoted to the study of the phenomena of mind, it needs to be insisted upon, that the inquirers themselves belong to the universe about which they inquire. And it should be clear—even a truism—that

A the inquirers present the grandest elements in the whole problem. For, to study, and to unfold even partially, the system of things existing, is to prove superiority in the midst of the system. It is to prove that there is reason in all things. And if so, the rational nature, which can unlock the secrets of the universe, most of all deserves attention.

From such elementary considerations, it is plain that all science is in a radical sense philosophy, and all philosophy science. It may even seem a needless distinction to speak of one form of inquiry as scientific, and of another as philosophic: ‘making one set of generalised results a science, another set a philosophy. Usage has, however, established the practice. And it is convenient to have the distinction. The sciences have come to be regarded as concerned with some department of the physical universe, in contrast with what pertains to the nature and laws of mind. This distinction has been held with sufficient definiteness for all practical purposes. Yet, science is so obviously a philosophy, that the old terminology was warranted which distinguished a Natural Philosophy from a Mental Philosophy,—a philosophy of nature from a philosophy of mind. On exactly the same ground we may speak of philosophy as a science. Scientific knowledge, the higher knowledge gathered by recognised scientific methods, cannot be restricted to certain spheres. Wherever observation is possible, and reflection as to the laws which regulate recognised facts, science is possible. If there may be a science of the formation of bone, muscle, and nerve, leading to the recognition of laws which operate in some manner quite beyond our experience, so may there be a science of perception, association, and inference, leading to the recognition of laws applicable to the facts of our experience. Man himself belongs to nature. The science of human life, in the full breadth of meaning belonging to the word “life” in this connection, has its place among the natural sciences. Physiology and Psychology when taken together are sciences of human life; they cannot be dissociated. Only when they are combined can we be said to have a science of the life of man. The claim is therefore a reasonable one, that the whole nature of man be included within the scope of natural science. I am far from thinking rl RELATIONS OF PHILOSOPHY AND SCIENCE. 3 that external observation alone will prove sufficient to guide us to a science of human life. But internal observation proceeds upon the same conditions, and is as entitled to confidence as external. By the blending of the two a science of human life may be reached, which will certainly be unattainable if either form of observation be exclusively employed.

Not unfrequently “scientific methods” have been claimed as belonging to the physical sciences alone. Mental philosophy, as treated in the works of well-known psychologists, has been ridiculed as if it had proceeded in disregard of “scientific methods.” The Scotch school of Philosophy has been specially reproached on this ground. The fallacy of such a charge is glaring. Psychologists may not have given as much attention to physiological facts as they should have done, but to charge them on that account with constructing their theories in dis regard of observation is obviously unwarrantable. Those who would fasten upon psychologists of former days such a charge as this, must be prepared to maintain that thought and recollection and volition are not facts, or that these are facts which do not occur according to law, or that both facts and laws are beyond the reach of scientific inquiry. There is no one who will hazard his reputation on the attempt to vindicate any one of these alternatives. The old psychologists most certainly did not proceed in neglect of the laws of observation and inference. And though there may be better reason for urging that physiology has been too much neglected by metaphysicians, the charge is often unreasonably pressed. You might as well charge the old physiologists with having neglected to use anesthetics in the vivisection employed in the study of the nerve system, as charge the old psycholoyists with neglecting the full use of physiology. The real state of the case is simply this—that physiology has never up till this time been in a position to give sufficient testimony as to the functions of nerve and brain to throw much light on philosophic problems. Even now the physiology ot nerve and brain is far from being in the advanced position which it must occupy before it can contribute towards the answer of many pressing questions concerned with mental action. Only quite recently have we had systematic investigation as to the possibility of localising functions in definite regions of the brain. And even yet there are very serious disputes as to what the results of accredited observations may involve. In these circumstances it hardly seems warrantable to charge against psychologists neglect of the teaching of physiology as bearing on the action of mind.

That psychologists have hitherto adopted an unreliable method of investigation cannot be maintained. If observation of facts, analysis for the discovery of distinct elements, classification of things similar, and inference resting on wide induction, are enumerated among “ scientific methods,” psychologists have regularly eniployed them all. By these methods they have come to very general agreement as to the rational and emotional nature belonging to our race. It has no doubt been said! that there is “no agreement ” among those who resort to internal observation ; but every one who is familiar with the works of psychologists knows that the statement is inaccurate. As to the laws of observation, of association, of reasoning, of pleasurable feeling, there is all but perfect agreement among them.

It is, indeed, the fact that psychologists have trusted to their own consciousness, that is, to their own experience, in seeking to ascertain the laws of mental life, and some physiologists tell us that consciousness is not trustworthy. It has even been said that “there is no witness who is so easily suborned to give false evidence as self-consciousness.”? But this is an assertion on which there is not agreement among physiologists, nor is it clear that evidence in its support can be gathered by use of scientific methods. It were indeed strange were any science to offer itself as defender of the dogma,—that man is not to trust his own experience. What may he trust if not this ? Take the most ordinary and commonplace tests. How but by consciousness does any man know that the blue appearance of his hands on a wintry morning is the accompaniment of coldness, or that perspiration is attendant on a high degree of heat 2 When a man says that he feels warm, is it a sad misfortune that “he appeals to a witness whose evidence can be taken by no one but himself”? Is it true that this is a witness “whose veracity cannot be tested”? To throw doubt upon experience

* Maudsley’s Physiology of Mind, 3d ed., p. 16. ce (Cd an va ral RELATIONS OF PHILOSOPHY AND SCIENCE. 5 is to deny the possibility of knowledge, and so of all science. When the psychologist trusts his consciousness he simply does what every man does,—what every man must do, who is not insane. Trust in consciousness is no speciality of psychologists, but the common prerogative of humanity. Here there can be no rational conflict between science and philosophy. Physiology must refer to consciousness in order to carry through its own investigations. A physiology of the senses must take account of the facts of consciousness connected with sight and hearing. Any scientific handling of the problem of localisation of functions in the brain is impossible without giving careful attention to the facts of individual consciousness. Of the host ot physiologists now engaged on this question, I am not aware of one who does not make habitual reference to the consciousness of others, besides placing constant reliance on his own. There seems to me but one sphere in which we find ourselves on debatable ground, that is, when we consider the case of the insane. And. it surely throws no discredit on consciousness, but is rather a testimony to its trustworthiness, if we encounter difficulties as to its testimony only when we come to deal with what is abnormal in life. But even here there are only complications, as the result of disturbance from an abnormal physical condition. If we disentangle these complications, we shall find that the trustworthiness of consciousness is confirmed. In our asylums for the insane, administration does not proceed on the assumption that the consciousness of the patients is not reliable. There is not a physician in any one of these Asylums who does not found his diagnosis on the assumption of the reliability of his patient’s consciousness. Even where there is the most extraordinary hallucination, the physician does not treat his patient as a cheat who is playing off tricks on the medical officers. On the contrary, he distinguishes between attempted deception and real hallucination. In regarding the hallucination as fact, he takes the consciousness of the deluded person as a reliable witness, and proceeds to consider what may be the source of the acknowledged hallucination. On this basis the physician prescribes, and he is vindicated in the assumption on which he proceeds by the number of cures he effects. On this same admission are based the rational methods of treatment, now accepted as the only methods which can pass for scientific. All the prescriptions and forms of discipline familiar in asylums . for the insane are used in accordance with observation, and that is based not only on what the physician sees, but also on what the patient says. ,