Introduction to psychological theory

Introduction

TO

PSYCHOLOGICAL THEORY

BY

BOEDER P. BOAVNE

PROFESSOR OF PHILOSOPHY IN BOSTON UNIVERSITY AUTHOR OF "METAPHYSICS"

I- i

NEW YORK HARPER k BROTHERS, FRANKLIN SQUARE

Copyright, 1886, by Harper & Brothers.

All rights reserved.

Preface

The aim of this work is given in its title. First, it is an " introduction " only, and does not go into the details or the literature of the subject. The aim is to point out the highways of psychology, rather than its myriad byways. Secondly, it is an " introduction to psychological theory ," and aims less at a knowledge of facts than at an understanding of principles. Until principles are settled there is no bar to the most fantastic theories and interpretations.

These principles being illustrated in the most common facts of experience, it is not necessary to psychological insight to make an anthology of madhouse and hospital stories. Such a procedure has about the same relation to psychology that the various books of " wonders " or the " brilliant experiments " of the popular lecturer have to sober physical science. An odor of quackery is perceptible in both cases.

The plan of the work precludes much attention to physiological psychology. Whatever the merits of this science may be, it presupposes pure psychology. If our aim is to give a physiological explanation of psychological facts,

VI PREFACE.

we must first know the facts. Or if our aim is the more modest one of finding the physical conditions or attendants of mental facts, again we must know the facts. But this knowledge is not possible by the way of physiology, and in any case the mental facts remain what they always were. Their likenesses and differences and essential nature would not be changed if physiology were supreme. Even the " new psychology " would not give us new mental facts, but only a new interpretation of the old facts. The Zeitgeist itself begins at last to see this ; and the naive onslaughts on the " old psychology " are happily growing fewer. Psychological literature shows very marked progress in this respect within the last twenty years. Physiology remains a most estimable science, but the physiological reconstruction of psychology has been postponed. The study of the physical conditions of our mental life has a pathological and practical importance ; but it does not promise any valuable psychological results, at least for those who can distinguish between the physical conditions and the mental facts which they condition.

The limitation of plan involves many omissions ; and in these there will seem to be a measure of arbitrariness. Hence many will not find here what they want, and probably still more will find what they do not want. There seems to be no way of adjusting so grave a difficulty except by maintaining, on the one hand, freedom to publish, and, on the other, freedom not to read.

Borden P. Bowne.

Boston, September, 1886.

Contents

INTRODUCTION.

Definition of Psychology, p. 1. — Possible Directions of Psychological Study, p. 1. — Psychology mainly an Introspective Science, p. 2. — Objections to the Introspective Method, p. 3. — Reasons for the slow Growth of Psychology, p. 4.

Chapter I

Pteality of Self the Condition of the Mental Life, p. 11. — Objections considered, p. 11. — Impossibility of Eational Consciousness apart from an Abiding Self, p. 12. — A Word on Method, p. 14. — Definition of Materialism, p. 15. — Materialism unclear in its Meaning, p. 16. —Ambiguity of the Facts of Mental Dependence, p. 18.— Difficulties of Materialism, p. 19. — Hylozoistic Materialism, p. 21. — Relation of Hylozoism to Physics, p. 22. — Untenability of Hylozoistic Materialism, p. 25. — Bearing of Materialism on Life and Action, p. 30. — Bearing of Materialism on Knowledge, p. 31. — Scepticism involved in Materialism, p. 34. — Man a Dual Being, » p. 36. —Value of this View, p. 36.

Vili CONTENTS.

Chapter II. PAGE

Physical Conditions of Sensation, p. 40. — Sensation not explained by its Physical Conditions, p. 40. — Forms of Nervous Stimulus, p. 41.

— Attempts to explain Differences of Sensation, p. 43. — Our Ignorance of Nervous Action no Psychological Loss, p. 48. — Relation of Sensation to Stimulus, p. 49. — Weber's Facts and Fechner's Theory, p. 50. — Difficulties of Fechner's Law, p. 52. — Interpretations of Fechner's Law, p. 53. — Differences in Simple Sensations, p. 56. — Double Aspect of Sensations, p. 58. — Organic Sensations, p. 59. — Source of the Sensations arising from Motion, p. 59. — Arguments for Sub-conscious Sensations, p. 62. — Criticism of the Same, p. 65.

— Simplicity of Sensations, p. 69. — Unclearness of the Doctrine, p. 70.

Chapter III

Facts of Reproduction, p. 73. — Two Classes of Theories, p. 75. — Herbart's Theory, p. 76. — Ambiguity and Difficulties of Herbart's Theory, p. 77. — Uncertainty of the English Associationalists, p. 82. — Physiological Theories of Reproduction, p. 83. — Shortcomings of all Cerebral Theories, p. 84. — Failure of every Theory to give a true Insight, p. 86. — Statement of Results, p. 87. — Laws of Association, p. 90. — The Laws criticised, p. 90. — Sub-conscious Association, p. 96.

Appendix to Chapter III

Forms and Implications of the Theory, p. 99. — Complexity of the Cell Theory, p. 101. Difficulty of keeping Impressions separated, p. 104. — Obscurity of the Theory on Important Points, p. 105. — No Account given of Actual Association, p. 107. — Physiological Difficulties, p. 109. —Habit Form of the Cerebral Theory, p. 111. — Difficulties of this View, p. 112. — Sense in which the Brain is the Organ of Memory, p. 113.

CONTENTS. IX

Chapter IV. PAGE

The Two Schools of Psychology, p. 115. — Psychological and Philosophical Aspect of their Differences, p. 116. — Primal Shortcoming of Sensationalism, p. 118. — Judgments cannot arise through Association alone, p. 119. — Two Distinct Processes in the Mental Life, p. 121. — Ambiguity in the Facts of Mental Development overlooked by Sensationalists, p. 123. — The Categories, p. 126. — Time, p. 127.

— Time not a Quality of Mental States, nor an Abstraction from them, p. 128. — The Sequence of Ideas not the Idea of Sequence, p. 128. — Memory not the Source of the Idea, p. 129. — The Idea of Time not dependent on the Idea of Causation, p. 131. — Fundamentally, Time is a Law of Mental Synthesis, p. 131. — Space, p. 133.

— Different Views of Space, p. 133. — Associational View, p. 134.

— Ambiguity and Untenability of this View, p. 135. — Superficiality of tbe Common View, p. 113. — The Idea of Space not explained by the Extension of the Nerves or by the Extension of the Soul, p. 141.

— The Source of the Idea must be sought for in the Nature of the Mind, p. 148. — Space essentially a Law of Mental Synthesis, p. 149.

— The Unity and Infinity of Space a Consequence of this Law, p. 149.

— Relation of Sense Experience to the Idea, p. 151. — iV-dimensional Space, p. 151. — Number, p. 153. — Number purely a Mental Product, p. 153. — Failure of the Attempts to deduce it from Sense Experience, p. 154. — Number as the Science of Pure Time, p. 156. — Substance, p. 158. — This Idea not derived from the Senses, p. 158. — Sensationalist Doctrine of Substance, p. 160. — Criticism of the Same, p. 160. — Cause, p. 165. — Criticism of the Sensational Theory, p. 167. — Claim that the Idea of Causation arises only from our Volitional Activity, p. 171. — The Truth in this Claim, p. 172.

Appendix to Chapter IV 175

Attempt to found Sensationalism on the Experience of the Race, p. 175. — Mutual Opposition of Sensationalism and Materialism, p. 175. — Difficulty of connecting the Experience of the Individual with that of the Race, p. 178. — Heredity the Problem, not its Solution, p. 178. — Ambiguity of the Facts, p. 178. — Inability of Heredity to create New Ideas, p. 180. — Mechanical Nature of the Doctrine, p. 180.

X CONTENTS.

Chapter V. PAGE

Feeling undefinable, p. 182. — Feeling cannot be deduced, p. 183. — Feeling cannot be understood through its Conditions, p. 186. — Physical Feelings, p. 188. — Obscurity of the Nervous Processes which condition them, p. 189. — No satisfactory Classification of the Feelings which have only a Mental Source, p. 191. — Mental Feelings as Functional, p. 191. — Emptiness of this Conception when made Universal, p. 193. — The Ego Feelings, p. 193. — Dependence of Feeling on its Relation to Self-consciousness, p. 194. — The Social Feelings, p. 195. — Attempts to deduce them from Selfish Feeling, p. 195. — Relation of the Ego Feelings to Social Relations, p. 197.

— ^Esthetic Feeling, p. 198. — ^Esthetic Judgments founded on ^Esthetic Feeling, p. 198. — Various Forms of ^Esthetic Feeling, p. 199. — Significance of Association for ^Esthetics, p. 200. — Reasons for the Diversity of ^Esthetic Judgments, p. 201. — Why do Objects please us aesthetically ? p. 201. — Insufficiency of Physiological Explanations, p. 202. — Failure of Attempts to base ^Esthetics on a Single Principle, p. 203. — Uncertainty of the Boundaries of the ^Esthetic Realm, p. 204. — The Moral Feelings, p. 205. — Two Directions of Ethical Study, p. 206. — The basal Ethical Fact, p. 206. — Double Standard of Ethical Judgment, p. 207. — Deductions and Reductions of the Moral Sentiments, p. 209. — Religious Feeling, p. 210. — Theories of the same, p. 211. — The Desires, p. 214. — The Object of Desire, p. 214. — Pleasures not Commensurable, p. 215. — Direction and Control of Feeling, p. 216. — Transition to Willing, p. 217.

Chapter VI

Not all Activity is Volitional, p. 220. — Constitutional Activity, p. 220.

— Volition indefinable, p. 221. — Volition distinguished from its Psychological Attendants, p. 221. — Volition implies Consciousness, p. 222. — In Spontaneous Thought Volition regarded as Free, p. 222.

— What this Freedom means, p. 223. — Opposing Conceptions, ]). 223. — Determinism not founded on Consciousness, p. 225. — Bearing of the same on Action and Knowledge, p. 226. — Reasons for Determinism, p. 228. — The Problem speculatively insoluble,

CONTENTS. XI

PAGE

p. 230. — Various Misunderstandings, p. 231. — Freedom implied as a Condition of Rational and Social Life, p. 232. — Limitation of Freedom, p. 233.

Chapter VII

Definitions of Consciousness tautologous, p. 235. — Traditional Confusion, p. 235. — Consciousness not a Faculty, p. 237. — Antithesis of Subject and Object the Universal Form of Consciousness, p. 238. — Objections by Sensationalism, p. 238. — Varying Degrees of Consciousness, p. 239. — Consciousness dependent on Thought as well as on the Sensibility, p. 241. — Misunderstanding of the Antithesis of Subject and Object, p. 242. — The two Factors of Self-consciousness, p. 244. — The Conception of Self not an Experience of Self, p. 245. — Self-experience admits of no Deduction, p. 246. — Development of Self-experience into Self-knowledge, p. 218.

Chapter I

Perception a Complex Process, p. 253. — Perception a Reaction of the Mind against External Action, p. 254. — This External Action no Copy of the Object, p. 255. — This Fact covered up with Figures of Speech, p. 256. — Implications of Valid Perception, p. 258. — Possibility of Error, p. 259. — The Perception of Things and that of Space Relations arise together, p. 260. — Difficulty of determining the Localizing Power of the Senses when taken separately, p. 261. — Complete Perception dependent on Classification, p. 262. — Distinction between the Appearance and the Thing, p. 263. — Origin of the Acquired Perceptions, p. 263. — Source of Sense Illusions, p. 264. Association in Perception, p. 265. — Use made by Berkeley of this Principle, p. 266. — Dependence of Perception on Reproduction, p. 268.

Xll CONTENTS.

Chapter II. PAGE

No consistent Terminology, p. 271. — Differences of Memory, Fantasy, and Imagination, p. 271. — Memory follows the Order of Mental Development, p. 272. — Laws of Menioiy, p. 273. — The Possibility of reproduction depends on the Nature of the Original Experience, p. 274. — Differences in Memory, p. 275. — The Fantasy, p. 276. — Significance of the Imagination for the Rational Life, p. 277. — Control of Reproduction, p. 278.

Chapter III

Two Stages of Thought, p. 280. — Relation of the Judgment to Knowledge, p. 281. — Relation of the Universal to the Judgment, p. 281. — Conditions of the Universal, p. 282. — Objections from the Associationalists, p. 282. — Thought and Language, p. 283. — Abstraction, p. 281. — Advantage and Disadvantage of Language, p. 285. — Genesis of Judgments, p. 285. — The Judgment in Formal Logic, p. 287. — Artificial Nature of the Logical Doctrine, p. 288. — Truth and Error, p. 290. — Nature of Inference, p. 292. — The Doctrine of Inference in Formal Logic artificial and arbitrary, p. 293. — Concerning Intuitions, p. 294. — Two Questions to be distinguished, p. 294. — Mathematics a Stumbling-block to Empiricism, p. 294. — Belief, p. 296. — Most Beliefs represent, not reasoned Truths, but practical Assumptions, p. 297.

Chapter IY.

Problem defined, p. 298. — All Interaction mysterious, p. 298. — Seat of the Soul, p. 299. — Meaning of the Question, p. 299. — As commonly understood the Question both idle and empty, p. 300. — Use of the Body by the Soul, p. 301. — Movements arising apart from Volition, p. 301. — Significance of the Mind for Physical Development, p. 304. — Two Classes of Physical Habits, p. 305. — The Soul as the Ground of Physical Structure, p. 306. — Cerebral Localization of Mental Functions, p. 307. — Nervous Action in Mental Work,

CONTENTS. Xlll

PAGE p. 308. — Thought not a Transformation of Nervous Energy, p. 309. — Significance of the Body for the Mental Life, p. 311. — Can the Mental Life go on apart from the Body ? p. 315. — Question admits of no Speculative Solution, p. 316.

Chapter V

Cause of Sleep not fully understood, p. 319. — Depth of Sleep, p. 320. — Fantastic Nature of Dreams, p. 320. — Origin of Dreams in Actual Sensations, p. 321. — Material of Dreams drawn from waking Experience, p. 322. — No single Explanation of Dreams possible, p. 322. — Is the Mind ever Inactive ? p. 323. — The Hypnotic State, p. 325. — Insanity, p. 326. — Its Psychological Features, p. 326. — Grounds of Insanity, p. 327. — Extraordinary Mental Powers, p. 328.

INTRODUCTION.

Psychology deals with mental facts and processes. It aims to describe and classify those facts and processes, to discover and state their laws, and to form some theory concerning their origin and cause. Corresponding to this complex aim, psychology, like all other sciences, may be descriptive and theoretical. We may content ourselves with simply describing and classifying the facts and processes. The result is empirical psychology. From this as a starting-point we may go on to theorize concerning the origin and causes of the facts and processes discovered. The result is theoretical, or philosophical, psychology. But in psychology, as in most other sciences, these two factors, though logically successive, are practically contemporaneous. No science completes its collection of facts before it begins to theorize ; but the study of fact and the formation of theory go together. This is especially true in psychology, where the statement of the facts themselves often involves a theory.

Psychological study may take several directions : — 1. We may study the facts and laws of mind in general, without reference to individual peculiarities or to concrete application. In this case the aim is to discover the essential facts and factors of the mental life. Bv observation we learn the facts and processes ; by analysis we seek to decompose them into their ultimate elements ; and, finally, we seek to exhibit the actual mental life as a synthesis of these elements. The product of such study is pure or abstract psychology.

2. The mental life is not perfect from the start, but is subject to a law of growth. We may study it, then, from the genetic side, and trace the order of its unfolding. Such study would have especial significance for the theory of education. Some speculators have thought it possible by this method, not merely to discover the order of temporal development, but also to deduce the later stages as necessary results of the earlier ones. We shall find reasons for doubting this view.

3. The mental life is physically conditioned ; and, instead of studying mental facts by themselves, we may study them in relation to the organism. This gives rise to a border science, physiological psychology. This does not study physiology in general, but physiology in its relation to mental facts. Nor does it study psychology in general, but psychology as conditioned by the organism.

Pure psychology is plainly the presupposition of all other forms of psychological study ; as pure logic or pure mechanics is the presupposition of applied logic or applied mechanics. Our work will be mainly in pure psychology, partly descriptive, partly theoretical, and not without some reference to physiology.

The facts of the objective sciences are discovered through the senses. The facts of psychology arc chiefly revealed only in consciousness. Instead of looking without to find them, we look within. Our method, therefore, must be mainly introspective. Mind can be studied to some extent in history, in institutions, in literature, and especially in language. In these we see the mind manifesting its nature, and uttering its spontaneous and unsophisticated convic-

INTRODUCTION. 6

tions. Language abounds in psychological theories and classifications, which serve as the starting-point even of scientific psychology. Thought, feeling, and volition ; sensation, emotion, and understanding; desire, choice, and effort ; body, soul, and spirit, — are illustrations. Such terms represent classifications, distinctions, and theories produced by the spontaneous thinking of mankind. Again, the structure of language itself is an incarnation of the laws of thought ; so much so, that Aristotle sought to determine the essential categories of thinking by an analysis of grammatical forms. The noun, the adjective, and the active verb are but the reappearance under the forms of language of the thought-forms of substance and attribute, cause and effect. In this sense there can be an objective study of thought. This does not mean, of course, that mind or thought can be presented to the senses ; but only that the nature of mind can be studied in its products.

Nevertheless, all our knowledge of mind derived from its objective study must come back to consciousness, either for its meaning or for its verification. No language concerning mental facts is intelligible unless we have had experience of the facts for ourselves. No theory of them is verified until we have compared it with the facts in our own consciousness and have found them to agree. Psychology, then, is finally based on introspection. It is a subjective rather than an objective science.

This fact has been made the ground for much objection. Some have denied the possibility of inspecting consciousness at all ; others have denied the trustworthiness of consciousness. According to the latter, consciousness cannot even tell us whether we are cold or hot. The former claim has the slight psychological foundation that many mental states, pre-eminently emotions, cannot be directly inspected without changing their character to some extent ; and therefore they have to be indirectly studied in memory. The latter claim has the slight historical justification that careless writers have often extended consciousness beyond its proper limits ; so that, instead of distinguishing between the facts of consciousness and their interpretation, they have made consciousness cover both. The proper facts of consciousness admit of no scepticism. The one who feels cold is cold ; but it may be that this feeling, instead of its ordinary antecedent, has an abnormal state of the nervous system as its cause. We trust the consciousness even of the insane ; doubt concerns only its interpretation. Remembering these limitations, any doubt of the trustworthiness of consciousness must seem palpably and flagrantly absurd.

Mental facts are nearest of all, and yet psychology develops slowly. The objective sciences are of an earlier birth and a more rapid growth. This is due to several facts : —

1. The mind is objective in its procedure, and thinks of itself last. We tend to lose ourselves in our objects ; and the processes of knowing are so immediate, that it never occurs to us that there is a process. This fact has the highest significance for mental health and development. The mind is taken out of itself and introduced to the great world of things, the knowledge of which is to be its chief occupation and the great source of its growth. The implicit trust of the mind in knowledge is shaken only as it stumbles upon contradictions and absurdities, and is forced thereby, to analyze its processes and revise its ;i ^sumptions.

2. The phenomena are complicated, and often admit of no description. Shades of feeling and emotion may be felt, but not described. Language, too, is formed under the influence of external objects, and hence is vague, and often misleading, in its application to mental states. Moreover, the mind, because of its objective tendency, becomes

INTRODUCTION. 6

disinclined to look within. Our mental states do not stand out in consciousness with the sharpness of objects in space. Hence the paradox, that there is nothing so hard to study as ourselves.

3. The facts admit of no exact measurement. Physical science depends especially upon measurement, either of size, duration, weight, or intensity. Its facts and laws first become fruitful when they become numerical. The fact of gravitation was known long before Newton, and was of no significance. It was the discovery of its numerical law which first gave it meaning. But thoughts and feelings have no size; and their intensity admits of no exact numerical determination.

4. Psychology admits of almost no experiment. In physiological psychology a little experiment is possible ; but in pure psychology no significant experiments can be made. It is, then, neither a mathematical, nor a deductive, nor an experimental science. We can only aim to describe and classify the facts, and to form some conception of their cause. On these accounts many have been pleased to deny that psychology is a science at all. They should rather say that it is not a certain kind of science. A systematic exposition of a certain set of facts, and a theorizing on them in accordance with their nature, constitute the science of that set of facts. It is only the mentally one-eyed who insist that all facts shall be treated by the same method, regardless of differences of nature.

No one has immediate knowledge of any mental life but his own. The mental life of all others is absolutely hidden from our senses. Their thoughts and feelings are open to no direct inspection. All we can see in connection with others is sundry changes and movements of the organism ; and all we know of their inner life is reached by analogical inference, whereby we assimilate it to our own. Nor is it easy to find physical marks which certainly denote intelligence. In the case of man, they consist chiefly in the voluntary movements and in language. For the animals, we have only the voluntary movements. In both cases, the facts of reflex action often make it doubtful whether what we call voluntary movements are really such ; and in both cases, also, their interpretation must be learned from within. It is plain, then, that the starting-point of psychology must be the analysis of the individual consciousness. Oversight of this patent fact has led to the fancy that psychology ought to begin by studying the mental phenomena of the lower animals. The inverted nature of the procedure is apparent; and the result is anthropomorphism in biology. We first assimilate the animal mind to the human mind ; and then we are quite ready to comprehend the latter as the outcome of the former.

But, on the other hand, no complete knowledge of the human mind can be gained by a study of the individual consciousness alone. This consciousness itself is evoked only under social conditions ; and the individual is never a complete or perfect specimen of the race. To escape the narrowness and one-sidedness of individualism we need to go out into the open field of the world, — into life, and history, and literature. Only thus can we eliminate individual variations from the type, and get some conception of the human mind in general, as distinct from its imperfect specimens.

In beginning our study several roads open before us. We might recite the various schemes of psychological classification, and select some one as a guide for our further study. Or we might observe that consciousness is a condition of all mental operations, and begin with a general discussion of the nature and conditions of consciousness. We shall do better, however, to postpone these questions and follow another order. We begin with a discussion of

INTRODUCTION. 7

the subject of the mental life ; then we pass to the impressions which that subject receives from without, and with which the mental life begins ; and, finally, we consider the complex action and reaction upon those impressions in which the developed mental life consists. And first of all, we discuss the subject and the factors of the mental life, leaving their combination for later study.

PART I.

THE FACTORS OF THE MENTAL LIFE.

PART I.

THE FACTORS OF THE MENTAL LIFE.

Chapter I. The Subject Of The Mental Life

In all mental experience the self appears as the subject of the mental state ; and the state is referred to the self as its subject. There is no such thing in experience as pure feeling, or knowing, or willing, without a subject that feels, or knows, or wills. Hence we may say that the simplest mental fact is at least double, involving a mental state and a subject of which it is a state. Thoughts and feelings apart from something that thinks and feels are unreal abstractions, like motion apart from something that moves. What is this something!: ?

In spontaneous thought and consciousness the mental subject is given as active and abiding ; and the race has constructed various names for it, as mind, soul, spirit, and their equivalents, to indicate its reality. The whole structure of thought and language also implies it. This conception of the mental subject we believe to be correct. It is disputed, however, on two general grounds : —

1. All mental states do not involve a reference to self as their subject.

2. The self, or mental subject, is only a compound product of mental states, and hence is subsequent to its components.

The first objection properly refers to the philosophy of self-consciousness. It does not deny that the mental acts and states are really acts and states of a substantial mind. It only questions whether they always contain a conscious reference to self, or involve self-consciousness. We postpone its consideration, therefore, to a later chapter.

The second claim, so far as it differs from the first, denies the existence of any substantial mind, and regards the mind only as a collective term for the sum of mental facts. As a rule, these mental facts are viewed as sensations, either simple or compounded. Thoughts and feelings exist ; but there is properly nothing that thinks and feels.

To this claim the obvious objection is, that we know nothing of mental states, sensational or otherwise, except as affections of some mental subject which has them. Moreover, we never can know of them apart from such connection. Not in the case of others ; for mental facts can never be seen from the outside. Not in our own case ; for then they would be known as ours. There is strictly nothing in experience to suggest that mental states can exist by themselves like things ; on the contrary, experience declares that there must always be something which has them. The opposite view is not based upon experience, but is purely a deduction from a speculative theory. In addition, thought breaks down in the attempt to construe it. Mental states are first broken from the only connection in which they have any meaning; and then are mistaken for the ground of their own condition.

Again, allowing that they may exist apart from a subject, there is no way of accounting for the unity of the mental life. Let a, b, c, d, e, etc. be a set of sensations without any common subject, M; there is no way of uniting them in a common consciousness. If coexistent, they cannot be known as such ; for no one knows anything of the others, each being only a particular sensation. For the same reason, they cannot be known as sequent. If they were the states of a common subject, M, they might be grasped in a common consciousness and compared as coexistent or sequent, like or unlike ; but otherwise they remain external to one another and without any possibility of progress.

A concrete illustration may make this clearer. Let, then, a, b, c, and d be respectively a sensation of color, of odor, of taste, and of sound. Plainly no consciousness can be built out of these elements. The color knows nothing of the odor; the taste knows nothing of the sound. Each is a particular and isolated unit ; and must remain so until some common subject, M, is given, in the unity of whose consciousness these elements may be united. For as long as a, b, c, etc. are all, there is no common consciousness, and hence no rational consciousness at all. We conclude, then, that the mental life, both in its elements and in its combinations, must have a subject. It is not only unintelligible, it is impossible, without it.