"If by this inquiry into the nature of the understanding I can discover the powers thereof, how far they reach, to what things they are in any degree proportionate, and where they fail us, I suppose it may be of use to prevail with the busy mind of man to be more cautious in meddling with things exceeding its comprehension: to stop when it is at the utmost extent of its tether; and to sit down in quiet ignorance of those things which, upon examination, are proved to be beyond the reach of our capacities. We should not then, perhaps, be so forward, out of an affectation of universal knowledge, to raise questions and perplex ourselves and others with disputes about things to which our understandings are not suited, and of which we cannot frame in our minds any clear and distinct perception, or whereof (as it has, perhaps, too often happened) we have not any notion at all.... Men may find matter sufficient to busy their heads and employ their hands with variety, delight, and satisfaction, if they will not boldly quarrel with their own constitution and throw away the blessings their hands are filled with because they are not big enough to grasp everything. We shall not have much reason to complain of the narrowness of our minds, if we will but employ them about what may be of use to us: for of that they are very capable: and it will be an unpardonable, as well as a childish peevishness, if we under-value the advantages of our knowledge, and neglect to improve it to the ends for which it was given us, because there are some things that are set out of the reach of it. It will be no excuse to an idle and untoward servant who would not attend to his business by candlelight, to plead that he had not broad sunshine. The candle that is set up in us shines bright enough for all our purposes.... Our business here is not to know all things, but those which concern our conduct."[16]

Hume develops the same fundamental conception in a somewhat different way, and with a more definite indication of the practical benefits which may be expected from a critical philosophy. The first and second parts of the twelfth section of the Inquiry are devoted to a condemnation of excessive scepticism, or Pyrrhonism, with which Hume couples a caricature of the Cartesian doubt; but, in the third part, a certain "mitigated scepticism" is recommended and adopted, under the title of "academical philosophy." After pointing out that a knowledge of the infirmities of the human understanding, even in its most perfect state, and when most accurate and cautious in its determinations, is the best check upon the tendency to dogmatism, Hume continues:—

"Another species of mitigated scepticism, which may be of advantage to mankind, and which maybe the natural result of the PYRRHONIAN doubts and scruples, is the limitation of our inquiries to such subjects as are best adapted to the narrow capacity of human understanding. The imagination of man is naturally sublime, delighted with whatever is remote and extraordinary, and running, without control, into the most distant parts of space and time in order to avoid the objects which custom has rendered too familiar to it. A correct judgment observes a contrary method, and, avoiding all distant and high inquiries, confines itself to common life, and to such subjects as fall under daily practice and experience; leaving the more sublime topics to the embellishment of poets and orators, or to the arts of priests and politicians. To bring us to so salutary a determination, nothing can be more serviceable than to be once thoroughly convinced of the force of the PYRRHONIAN doubt, and of the impossibility that anything but the strong power of natural instinct could free us from it. Those who have a propensity to philosophy will still continue their researches; because they reflect, that, besides the immediate pleasure attending such an occupation, philosophical decisions are nothing but the reflections of common life, methodised and corrected. But they will never be tempted to go beyond common life, so long as they consider the imperfection of those faculties which they employ, their narrow reach, and their inaccurate operations. While we cannot give a satisfactory reason why we believe, after a thousand experiments, that a stone will fall or fire burn; can we ever satisfy ourselves concerning any determination which we may form with regard to the origin of worlds and the situation of nature from and to eternity?"—(IV. pp. 189—90.)

But further, it is the business of criticism not only to keep watch over the vagaries of philosophy, but to do the duty of police in the whole world of thought. Wherever it espies sophistry or superstition they are to be bidden to stand; nay, they are to be followed to their very dens and there apprehended and exterminated, as Othello smothered Desdemona, "else she'll betray more men."

Hume warms into eloquence as he sets forth the labours meet for the strength and the courage of the Hercules of "mitigated scepticism."

"Here, indeed, lies the justest and most plausible objection against a considerable part of metaphysics, that they are not properly a science, but arise either from the fruitless efforts of human vanity, which would penetrate into subjects utterly inaccessible to the understanding, or from the craft of popular superstitions, which, being unable to defend themselves on fair ground, raise these entangling brambles to cover and protect their weakness. Chased from the open country, these robbers fly into the forest, and lie in wait to break in upon every unguarded avenue of the mind and overwhelm it with religious fears and prejudices. The stoutest antagonist, if he remits his watch a moment, is oppressed; and many, through cowardice and folly, open the gates to the enemies, and willingly receive them with reverence and submission as their legal sovereigns.

"But is this a sufficient reason why philosophers should desist from such researches and leave superstition still in possession of her retreat? Is it not proper to draw an opposite conclusion, and perceive the necessity of carrying the war into the most secret recesses of the enemy?... The only method of freeing learning at once from these abstruse questions, is to inquire seriously into the nature of human understanding, and show, from an exact analysis of its powers and capacity, that it is by no means fitted for such remote and abstruse subjects. We must submit to this fatigue, in order to live at ease ever after; and must cultivate true metaphysics with some care, in order to destroy the false and adulterated."—(IV. pp. 10, 11.)

Near a century and a half has elapsed since these brave words were shaped by David Hume's pen; and the business of carrying the war into the enemy's camp has gone on but slowly. Like other campaigns, it long languished for want of a good base of operations. But since physical science, in the course of the last fifty years, has brought to the front an inexhaustible supply of heavy artillery of a new pattern, warranted to drive solid bolts of fact through the thickest skulls, things are looking better; though hardly more than the first faint flutterings of the dawn of the happy day, when superstition and false metaphysics shall be no more and reasonable folks may "live at ease," are as yet discernible by the enfants perdus of the outposts.

If, in thus conceiving the object and the limitations of philosophy, Hume shows himself the spiritual child and continuator of the work of Locke, he appears no less plainly as the parent of Kant and as the protagonist of that more modern way of thinking, which has been called "agnosticism," from its profession of an incapacity to discover the indispensable conditions of either positive or negative knowledge, in many propositions, respecting which, not only the vulgar, but philosophers of the more sanguine sort, revel in the luxury of unqualified assurance.

The aim of the Kritik der reinen Vernunft is essentially the same as that of the Treatise of Human Nature, by which indeed Kant was led to develop that "critical philosophy" with which his name and fame are indissolubly bound up: and, if the details of Kant's criticism differ from those of Hume, they coincide with them in their main result, which is the limitation of all knowledge of reality to the world of phenomena revealed to us by experience.

The philosopher of Koenigsberg epitomises the philosopher of Ninewells when he thus sums up the uses of philosophy:—

"The greatest and perhaps the sole use of all philosophy of pure reason is, after all, merely negative, since it serves, not as an organon for the enlargement [of knowledge], but as a discipline for its delimitation; and instead of discovering truth, has only the modest merit of preventing error."[17]

FOOTNOTES:

[14] In a letter to Hutcheson (September 17th, 1739) Hume remarks:—"There are different ways of examining the mind as well as the body. One may consider it either as an anatomist or as a painter: either to discover its most secret springs and principles, or to describe the grace and beauty of its actions;" and he proceeds to justify his own mode of looking at the moral sentiments from the anatomist's point of view.

[15] The manner in which Hume constantly refers to the results of the observation of the contents and the processes of his own mind clearly shows that he has here inadvertently overstated the case.

[16] Locke, An Essay concerning Human Understanding, Book I, chap. i, Sec.Sec. 4, 5, 6.

[17] Kritik der reinen Vernunft. Ed. Hartenstein, p. 256.



CHAPTER II.

THE CONTENTS OF THE MIND.

In the language of common life, the "mind" is spoken of as an entity, independent of the body, though resident in and closely connected with it, and endowed with numerous "faculties," such as sensibility, understanding, memory, volition, which stand in the same relation to the mind as the organs do to the body, and perform the functions of feeling, reasoning, remembering, and willing. Of these functions, some, such as sensation, are supposed to be merely passive—that is, they are called into existence by impressions, made upon the sensitive faculty by a material world of real objects, of which our sensations are supposed to give us pictures; others, such as the memory and the reasoning faculty, are considered to be partly passive and partly active; while volition is held to be potentially, if not always actually, a spontaneous activity.

The popular classification and terminology of the phenomena of consciousness, however, are by no means the first crude conceptions suggested by common sense, but rather a legacy, and, in many respects, a sufficiently damnosa haereditas, of ancient philosophy, more or less leavened by theology; which has incorporated itself with the common thought of later times, as the vices of the aristocracy of one age become those of the mob in the next. Very little attention to what passes in the mind is sufficient to show, that these conceptions involve assumptions of an extremely hypothetical character. And the first business of the student of psychology is to get rid of such prepossessions; to form conceptions of mental phenomena as they are given us by observation, without any hypothetical admixture, or with only so much as is definitely recognised and held subject to confirmation or otherwise; to classify these phenomena according to their clearly recognisable characters; and to adopt a nomenclature which suggests nothing beyond the results of observation. Thus chastened, observation of the mind makes us acquainted with nothing but certain events, facts, or phenomena (whichever name be preferred) which pass over the inward field of view in rapid and, as it may appear on careless inspection, in disorderly succession, like the shifting patterns of a kaleidoscope. To all these mental phenomena, or states of our consciousness,[18] Descartes gave the name of "thoughts,"[19] while Locke and Berkeley termed them "ideas." Hume, regarding this as an improper use of the word "idea," for which he proposes another employment, gives the general name of "perceptions" to all states of consciousness. Thus, whatever other signification we may see reason to attach to the word "mind," it is certain that it is a name which is employed to denote a series of perceptions; just as the word "tune," whatever else it may mean, denotes, in the first place, a succession of musical notes. Hume, indeed, goes further than others when he says that—

"What we call a mind is nothing but a heap or collection of different perceptions, united together by certain relations, and supposed, though falsely, to be endowed with a perfect simplicity and identity."—(I. p. 268.)

With this "nothing but," however, he obviously falls into the primal and perennial error of philosophical speculators—dogmatising from negative arguments. He may be right or wrong; but the most he, or anybody else, can prove in favour of his conclusion is, that we know nothing more of the mind than that it is a series of perceptions. Whether there is something in the mind that lies beyond the reach of observation; or whether perceptions themselves are the products of something which can be observed and which is not mind; are questions which can in nowise be settled by direct observation. Elsewhere, the objectionable hypothetical element of the definition of mind is less prominent:—

"The true idea of the human mind is to consider it as a system of different perceptions, or different existences, which are linked together by the relation of cause and effect, and mutually produce, destroy, influence and modify each other.... In this respect I cannot compare the soul more properly to anything than a republic or commonwealth, in which the several members are united by the reciprocal ties of government and subordination, and give rise to other persons who propagate the same republic in the incessant changes of its parts."—(I. p. 331).

But, leaving the question of the proper definition of mind open for the present, it is further a matter of direct observation, that, when we take a general survey of all our perceptions or states of consciousness, they naturally fall into sundry groups or classes. Of these classes, two are distinguished by Hume as of primary importance. All "perceptions," he says, are either "Impressions" or "Ideas."

Under "impressions" he includes "all our more lively perceptions, when we hear, see, feel, love, or will;" in other words, "all our sensations, passions, and emotions, as they make their first appearance in the soul" (I. p. 15).

"Ideas," on the other hand, are the faint images of impressions in thinking and reasoning, or of antecedent ideas.

Both impressions and ideas may be either simple, when they are incapable of further analysis, or complex, when they may be resolved into simpler constituents. All simple ideas are exact copies of impressions; but, in complex ideas, the arrangement of simple constituents may be different from that of the impressions of which those simple ideas are copies.

Thus the colours red and blue and the odour of a rose, are simple impressions; while the ideas of blue, of red, and of rose-odour are simple copies of these impressions. But a red rose gives us a complex impression, capable of resolution into the simple impressions of red colour, rose-scent, and numerous others; and we may have a complex idea, which is an accurate, though faint, copy of this complex impression. Once in possession of the ideas of a red rose and of the colour blue, we may, in imagination, substitute blue for red; and thus obtain a complex idea of a blue rose, which is not an actual copy of any complex impression, though all its elements are such copies.

Hume has been criticised for making the distinction of impressions and ideas to depend upon their relative strength or vivacity. Yet it would be hard to point out any other character by which the things signified can be distinguished. Any one who has paid attention to the curious subject of what are called "subjective sensations" will be familiar with examples of the extreme difficulty which sometimes attends the discrimination of ideas of sensation from impressions of sensation, when the ideas are very vivid, or the impressions are faint. Who has not "fancied" he heard a noise; or has not explained inattention to a real sound by saying, "I thought it was nothing but my fancy"? Even healthy persons are much more liable to both visual and auditory spectra—that is, ideas of vision and sound so vivid that they are taken for new impressions—than is commonly supposed; and, in some diseased states, ideas of sensible objects may assume all the vividness of reality.

If ideas are nothing but copies of impressions, arranged, either in the same order as that of the impressions from which they are derived, or in a different order, it follows that the ultimate analysis of the contents of the mind turns upon that of the impressions. According to Hume, these are of two kinds: either they are impressions of sensation, or they are impressions of reflection. The former are those afforded by the five senses, together with pleasure and pain. The latter are the passions or the emotions (which Hume employs as equivalent terms). Thus the elementary states of consciousness, the raw materials of knowledge, so to speak, are either sensations or emotions; and whatever we discover in the mind, beyond these elementary states of consciousness, results from the combinations and the metamorphoses which they undergo.

It is not a little strange that a thinker of Hume's capacity should have been satisfied with the results of a psychological analysis which regards some obvious compounds as elements, while it omits altogether a most important class of elementary states.

With respect to the former point, Spinoza's masterly examination of the Passions in the third part of the Ethics should have been known to Hume.[20] But, if he had been acquainted with that wonderful piece of psychological anatomy, he would have learned that the emotions and passions are all complex states, arising from the close association of ideas of pleasure or pain with other ideas; and, indeed, without going to Spinoza, his own acute discussion of the passions leads to the same result,[21] and is wholly inconsistent with his classification of those mental states among the primary uncompounded materials of consciousness.

If Hume's "impressions of reflection" are excluded from among the primary elements of consciousness, nothing is left but the impressions afforded by the five senses, with pleasure and pain. Putting aside the muscular sense, which had not come into view in Hume's time, the questions arise whether these are all the simple undecomposable materials of thought? or whether others exist of which Hume takes no cognizance.

Kant answered the latter question in the affirmative, in the Kritik der reinen Vernunft, and thereby made one of the greatest advances ever effected in philosophy; though it must be confessed that the German philosopher's exposition of his views is so perplexed in style, so burdened with the weight of a cumbrous and uncouth scholasticism, that it is easy to confound the unessential parts of his system with those which are of profound importance. His baggage train is bigger than his army, and the student who attacks him is too often led to suspect he has won a position when he has only captured a mob of useless camp-followers.

In his Principles of Psychology, Mr. Herbert Spencer appears to me to have brought out the essential truth which underlies Kant's doctrine in a far clearer manner than any one else; but, for the purpose of the present summary view of Hume's philosophy, it must suffice if I state the matter in my own way, giving the broad outlines, without entering into the details of a large and difficult discussion.

When a red light flashes across the field of vision, there arises in the mind an "impression of sensation"—which we call red. It appears to me that this sensation, red, is a something which may exist altogether independently of any other impression, or idea, as an individual existence. It is perfectly conceivable that a sentient being should have no sense but vision, and that he should have spent his existence in absolute darkness, with the exception of one solitary flash of red light. That momentary illumination would suffice to give him the impression under consideration; and the whole content of his consciousness might be that impression; and, if he were endowed with memory, its idea.

Such being the state of affairs, suppose a second flash of red light to follow the first. If there were no memory of the latter, the state of the mind on the second occasion would simply be a repetition of that which occurred before. There would be merely another impression.

But suppose memory to exist, and that an idea of the first impression is generated; then, if the supposed sentient being were like ourselves, there might arise in his mind two altogether new impressions. The one is the feeling of the succession of the two impressions, the other is the feeling of their similarity.

Yet a third case is conceivable. Suppose two flashes of red light to occur together, then a third feeling might arise which is neither succession nor similarity, but that which we call co-existence.

These feelings, or their contraries, are the foundation of everything that we call a relation. They are no more capable of being described than sensations are; and, as it appears to me, they are as little susceptible of analysis into simpler elements. Like simple tastes and smells, or feelings of pleasure and pain, they are ultimate irresolvable facts of conscious experience; and, if we follow the principle of Hume's nomenclature, they must be called impressions of relation. But it must be remembered, that they differ from the other impressions, in requiring the pre-existence of at least two of the latter. Though devoid of the slightest resemblance to the other impressions, they are, in a manner, generated by them. In fact, we may regard them as a kind of impressions of impressions; or as the sensations of an inner sense, which takes cognizance of the materials furnished to it by the outer senses.

Hume failed as completely as his predecessors had done to recognise the elementary character of impressions of relation; and, when he discusses relations, he falls into a chaos of confusion and self-contradiction.

In the Treatise, for example, (Book I., Sec. iv.) resemblance, contiguity in time and space, and cause and effect, are said to be the "uniting principles among ideas," "the bond of union" or "associating quality by which one idea naturally introduces another." Hume affirms that—

"These qualities produce an association among ideas, and upon the appearance of one idea naturally introduce another." They are "the principles of union or cohesion among our simple ideas, and, in the imagination, supply the place of that inseparable connection by which they are united in our memory. Here is a kind of attraction, which, in the mental world, will be found to have as extraordinary effects as in the natural, and to show itself in as many and as various forms. Its effects are everywhere conspicuous; but, as to its causes they are mostly unknown, and must be resolved into original qualities of human nature, which I pretend not to explain."—(I. p. 29.)

And at the end of this section Hume goes on to say—

"Amongst the effects of this union or association of ideas, there are none more remarkable than those complex ideas which are the common subjects of our thought and reasoning, and generally arise from some principle of union among our simple ideas. These complex ideas may be resolved into relations, modes, and substances."—(Ibid.)

In the next section, which is devoted to Relations, they are spoken of as qualities "by which two ideas are connected together in the imagination," or "which make objects admit of comparison," and seven kinds of relation are enumerated, namely, resemblance, identity, space and time, quantity or number, degrees of quality, contrariety, and cause and effect.

To the reader of Hume, whose conceptions are usually so clear, definite, and consistent, it is as unsatisfactory as it is surprising to meet with so much questionable and obscure phraseology in a small space. One and the same thing, for example, resemblance, is first called a "quality of an idea," and secondly a "complex idea." Surely it cannot be both. Ideas which have the qualities of "resemblance, contiguity, and cause and effect," are said to "attract one another" (save the mark!), and so become associated; though, in a subsequent part of the Treatise, Hume's great effort is to prove that the relation of cause and effect is a particular case of the process of association; that is to say, is a result of the process of which it is supposed to be the cause. Moreover, since, as Hume is never weary of reminding his readers, there is nothing in ideas save copies of impressions, the qualities of resemblance, contiguity, and so on, in the idea, must have existed in the impression of which that idea is a copy; and therefore they must be either sensations or emotions—from both of which classes they are excluded.

In fact, in one place, Hume himself has an insight into the real nature of relations. Speaking of equality, in the sense of a relation of quantity, he says—

"Since equality is a relation, it is not, strictly speaking, a property in the figures themselves, but arises merely from the comparison which the mind makes between them."—(I. p. 70.)

That is to say, when two impressions of equal figures are present, there arises in the mind a tertium quid, which is the perception of equality. On his own principles, Hume should therefore have placed this "perception" among the ideas of reflection. However, as we have seen, he expressly excludes everything but the emotions and the passions from this group.

It is necessary therefore to amend Hume's primary "geography of the mind" by the excision of one territory and the addition of another; and the elementary states of consciousness will stand thus:—

A. IMPRESSIONS. A. Sensations of a. Smell. b. Taste. c. Hearing. d. Sight. e. Touch. f. Resistance (the muscular sense). B. Pleasure and Pain. C. Relations. a. Co-existence. b. Succession. c. Similarity and dissimilarity. B. IDEAS. Copies, or reproductions in memory, of the foregoing.

And now the question arises, whether any, and if so what, portion of these contents of the mind are to be termed "knowledge."

According to Locke, "Knowledge is the perception of the agreement or disagreement of two ideas;" and Hume, though he does not say so in so many words, tacitly accepts the definition. It follows, that neither simple sensation, nor simple emotion, constitutes knowledge; but that, when impressions of relation are added to these impressions, or their ideas, knowledge arises; and that all knowledge is the knowledge of likenesses and unlikenesses, co-existences and successions.

It really matters very little in what sense terms are used, so long as the same meaning is always rigidly attached to them; and, therefore, it is hardly worth while to quarrel with this generally accepted, though very arbitrary, limitation of the signification of "knowledge." But, on the face of the matter, it is not obvious why the impression we call a relation should have a better claim to the title of knowledge, than that which we call a sensation or an emotion; and the restriction has this unfortunate result, that it excludes all the most intense states of consciousness from any claim to the title of "knowledge."

For example, on this view, pain, so violent and absorbing as to exclude all other forms of consciousness, is not knowledge; but becomes a part of knowledge the moment we think of it in relation to another pain, or to some other mental phenomenon. Surely this is somewhat inconvenient, for there is only a verbal difference between having a sensation and knowing one has it: they are simply two phrases for the same mental state.

But the "pure metaphysicians" make great capital out of the ambiguity. For, starting with the assumption that all knowledge is the perception of relations, and finding themselves, like mere common-sense folks, very much disposed to call sensation knowledge, they at once gratify that disposition and save their consistency, by declaring that even the simplest act of sensation contains two terms and a relation—the sensitive subject, the sensigenous object, and that masterful entity, the Ego. From which great triad, as from a gnostic Trinity, emanates an endless procession of other logical shadows and all the Fata Morgana of philosophical dreamland.

FOOTNOTES:

[18] "Consciousnesses" would be a better name, but it is awkward. I have elsewhere proposed psychoses as a substantive name for mental phenomena.

[19] As this has been denied, it may be as well to give Descartes's words: "Par le mot de penser, j'entends tout ce que se fait dans nous de telle sorte que nous l'apercevons immediatement par nous-memes: c'est pourquoi non-seulement entendre, vouloir, imaginer, mais aussi sentir, c'est le meme chose ici que penser."—Principes de Philosophie. Ed. Cousin. 57.

"Toutes les proprietes que nous trouvons en la chose qui pense ne sont que des facons differentes de penser."—Ibid. 96.

[20] On the whole, it is pleasant to find satisfactory evidence that Hume knew nothing of the works of Spinoza; for the invariably abusive manner in which he refers to that type of the philosophic hero is only to be excused, if it is to be excused, by sheer ignorance of his life and work.

[21] For example, in discussing pride and humility, Hume says:—

"According as our idea of ourselves is more or less advantageous, we feel either of these opposite affections, and are elated by pride or dejected with humility ... when self enters not into the consideration there is no room either for pride or humility." That is, pride is pleasure, and humility is pain, associated with certain conceptions of one's self; or, as Spinoza puts it:—"Superbia est de se prae amore sui plus justo sentire" ("amor" being "laetitia concomitante idea causae externae"); and "Humilitas est tristitia orta ex eo quod homo suam impotentiam sive imbecillitatem contemplatur."



CHAPTER III.

THE ORIGIN OF THE IMPRESSIONS.

Admitting that the sensations, the feelings of pleasure and pain, and those of relation, are the primary irresolvable states of consciousness, two further lines of investigation present themselves. The one leads us to seek the origin of these "impressions;" the other, to inquire into the nature of the steps by which they become metamorphosed into those compound states of consciousness, which so largely enter into our ordinary trains of thought.

With respect to the origin of impressions of sensation, Hume is not quite consistent with himself. In one place (I. p. 117) he says, that it is impossible to decide "whether they arise immediately from the object, or are produced by the creative power of the mind, or are derived from the Author of our being," thereby implying that realism and idealism are equally probable hypotheses. But, in fact, after the demonstration by Descartes, that the immediate antecedents of sensations are changes in the nervous system, with which our feelings have no sort of resemblance, the hypothesis that sensations "arise immediately from the object" was out of court; and that Hume fully admitted the Cartesian doctrine is apparent when he says (I. p. 272):—

"All our perceptions are dependent on our organs and the disposition of our nerves and animal spirits."

And again, though in relation to another question, he observes:—

"There are three different kinds of impressions conveyed by the senses. The first are those of the figure, bulk, motion, and solidity of bodies. The second those of colours, tastes, smells, sounds, heat, and cold. The third are the pains and pleasures that arise from the application of objects to our bodies, as by the cutting of our flesh with steel, and such like. Both philosophers and the vulgar suppose the first of these to have a distinct continued existence. The vulgar only regard the second as on the same footing. Both philosophers and the vulgar again esteem the third to be merely perceptions, and consequently interrupted and dependent beings.

"Now 'tis evident that, whatever may be our philosophical opinion, colour, sounds, heat, and cold, as far as appears to the senses, exist after the same manner with motion and solidity; and that the difference we make between them, in this respect, arises not from the mere perception. So strong is the prejudice for the distinct continued existence of the former qualities, that when the contrary opinion is advanced by modern philosophers, people imagine they can almost refute it from their reason and experience, and that their very senses contradict this philosophy. 'Tis also evident that colours, sounds, &c., are originally on the same footing with the pain that arises from steel, and pleasure that proceeds from a fire; and that the difference betwixt them is founded neither on perception nor reason, but on the imagination. For as they are confessed to be, both of them, nothing but perceptions arising from the particular configurations and motions of the parts of body, wherein possibly can their difference consist? Upon the whole, then, we may conclude that, as far as the senses are judges, all perceptions are the same in the manner of their existence."—(I. p. 250, 251.)

The last words of this passage are as much Berkeley's as Hume's. But, instead of following Berkeley in his deductions from the position thus laid down, Hume, as the preceding citation shows, fully adopted the conclusion to which all that we know of psychological physiology tends, that the origin of the elements of consciousness, no less than that of all its other states, is to be sought in bodily changes, the seat of which can only be placed in the brain. And, as Locke had already done with less effect, he states and refutes the arguments commonly brought against the possibility of a causal connexion between the modes of motion of the cerebral substance and states of consciousness, with great clearness:—

"From these hypotheses concerning the substance and local conjunction of our perceptions we may pass to another, which is more intelligible than the former, and more important than the latter, viz. concerning the cause of our perceptions. Matter and motion, 'tis commonly said in the schools, however varied, are still matter and motion, and produce only a difference in the position and situation of objects. Divide a body as often as you please, 'tis still body. Place it in any figure, nothing ever results but figure, or the relation of parts. Move it in any manner, you still find motion or a change of relation. 'Tis absurd to imagine that motion in a circle, for instance, should be nothing but merely motion in a circle; while motion in another direction, as in an ellipse, should also be a passion or moral reflection; that the shocking of two globular particles should become a sensation of pain, and that the meeting of the triangular ones should afford a pleasure. Now as these different shocks and variations and mixtures are the only changes of which matter is susceptible, and as these never afford us any idea of thought or perception, 'tis concluded to be impossible, that thought can ever be caused by matter.

"Few have been able to withstand the seeming evidence of this argument; and yet nothing in the world is more easy than to refute it. We need only reflect upon what has been proved at large, that we are never sensible of any connexion between causes and effects, and that 'tis only by our experience of their constant conjunction we can arrive at any knowledge of this relation. Now, as all objects which are not contrary are susceptible of a constant conjunction, and as no real objects are contrary, I have inferred from these principles (Part III. Sec. 15) that, to consider the matter a priori, anything may produce anything, and that we shall never discover a reason why any object may or may not be the cause of any other, however great, or however little, the resemblance may be betwixt them. This evidently destroys the precedent reasoning, concerning the cause of thought or perception. For though there appear no manner of connection betwixt motion and thought, the case is the same with all other causes and effects. Place one body of a pound weight on one end of a lever, and another body of the same weight on the other end; you will never find in these bodies any principle of motion dependent on their distance from the centre, more than of thought and perception. If you pretend, therefore, to prove, a priori, that such a position of bodies can never cause thought, because, turn it which way you will, it is nothing but a position of bodies: you must, by the same course of reasoning, conclude that it can never produce motion, since there is no more apparent connection in the one than in the other. But, as this latter conclusion is contrary to evident experience, and as 'tis possible we may have a like experience in the operations of the mind, and may perceive a constant conjunction of thought and motion, you reason too hastily when, from the mere consideration of the ideas, you conclude that 'tis impossible motion can ever produce thought, or a different position of parts give rise to a different passion or reflection. Nay, 'tis not only possible we may have such an experience, but 'tis certain we have it; since every one may perceive that the different dispositions of his body change his thoughts and sentiments. And should it be said that this depends on the union of soul and body, I would answer, that we must separate the question concerning the substance of the mind from that concerning the cause of its thought; and that, confining ourselves to the latter question, we find, by the comparing their ideas, that thought and motion are different from each other and by experience, that they are constantly united; which, being all the circumstances that enter into the idea of cause and effect, when applied to the operations of matter, we may certainly conclude that motion may be, and actually is, the cause of thought and perception."—(I. pp. 314-316.)

The upshot of all this is, that the "collection of perceptions," which constitutes the mind, is really a system of effects, the causes of which are to be sought in antecedent changes of the matter of the brain, just as the "collection of motions," which we call flying, is a system of effects, the causes of which are to be sought in the modes of motion of the matter of the muscles of the wings.

Hume, however, treats of this important topic only incidentally. He seems to have had very little acquaintance even with such physiology as was current in his time. At least, the only passage of his works, bearing on this subject, with which I am acquainted, contains nothing but a very odd version of the physiological views of Descartes:—

"When I received the relations of resemblance, contiguity, and causation, as principles of union among ideas, without examining into their causes, 'twas more in prosecution of my first maxim, that we must in the end rest contented with experience, than for want of something specious and plausible which I might have displayed on that subject. 'Twould have been easy to have made an imaginary dissection of the brain, and have shown why, upon our conception of any idea, the animal spirits run into all the contiguous traces and rouse up the other ideas that are related to it. But though I have neglected any advantage which I might have drawn from this topic in explaining the relations of ideas, I am afraid I must here have recourse to it, in order to account for the mistakes that arise from these relations. I shall therefore observe, that as the mind is endowed with the power of exciting any idea it pleases; whenever it despatches the spirits into that region of the brain in which the idea is placed; these spirits always excite the idea, when they run precisely into the proper traces and rummage that cell which belongs to the idea. But as their motion is seldom direct, and naturally turns a little to the one side or to the other; for this reason the animal spirits, falling into the contiguous traces, present other related ideas, in lieu of that which the mind desired at first to survey. This change we are not always sensible of; but continuing still the same train of thought, make use of the related idea which is presented to us and employ it in our reasonings, as if it were the same with what we demanded. This is the cause of many mistakes and sophisms in philosophy; as will naturally be imagined, and as it would be easy to show, if there was occasion."—(I. p. 88.)

Perhaps it is as well for Hume's fame that the occasion for further physiological speculations of this sort did not arise. But, while admitting the crudity of his notions and the strangeness of the language in which they are couched, it must in justice be remembered, that what are now known as the elements of the physiology of the nervous system were hardly dreamed of in the first half of the eighteenth century; and, as a further set off to Hume's credit, it must be noted that he grasped the fundamental truth, that the key to the comprehension of mental operations lies in the study of the molecular changes of the nervous apparatus by which they are originated.

Surely no one who is cognisant of the facts of the case, nowadays, doubts that the roots of psychology lie in the physiology of the nervous system. What we call the operations of the mind are functions of the brain, and the materials of consciousness are products of cerebral activity. Cabanis may have made use of crude and misleading phraseology when he said that the brain secretes thought as the liver secretes bile; but the conception which that much-abused phrase embodies is, nevertheless, far more consistent with fact than the popular notion that the mind is a metaphysical entity seated in the head, but as independent of the brain as a telegraph operator is of his instrument.

It is hardly necessary to point out that the doctrine just laid down is what is commonly called materialism. In fact, I am not sure that the adjective "crass," which appears to have a special charm for rhetorical sciolists, would not be applied to it. But it is, nevertheless, true that the doctrine contains nothing inconsistent with the purest idealism. For, as Hume remarks (as indeed Descartes had observed long before):—

"'Tis not our body we perceive when we regard our limbs and members, but certain impressions which enter by the senses; so that the ascribing a real and corporeal existence to these impressions, or to their objects, is an act of the mind as difficult to explain as that [the external existence of objects] which we examine at present."—(I. p. 249.)

Therefore, if we analyse the proposition that all mental phenomena are the effects or products of material phenomena, all that it means amounts to this; that whenever those states of consciousness which we call sensation, or emotion, or thought, come into existence, complete investigation will show good reason for the belief that they are preceded by those other phenomena of consciousness to which we give the names of matter and motion. All material changes appear, in the long run, to be modes of motion; but our knowledge of motion is nothing but that of a change in the place and order of our sensations; just as our knowledge of matter is restricted to those feelings of which we assume it to be the cause.

It has already been pointed out, that Hume must have admitted, and in fact does admit, the possibility that the mind is a Leibnitzian monad, or a Fichtean world-generating Ego, the universe of things being merely the picture produced by the evolution of the phenomena of consciousness. For any demonstration that can be given to the contrary effect, the "collection of perceptions" which makes up our consciousness may be an orderly phantasmagoria generated by the Ego, unfolding its successive scenes on the background of the abyss of nothingness; as a firework, which is but cunningly arranged combustibles, grows from a spark into a coruscation, and from a coruscation into figures, and words, and cascades of devouring fire, and then vanishes into the darkness of the night.

On the other hand, it must no less readily be allowed that, for anything that can be proved to the contrary, there may be a real something which is the cause of all our impressions; that sensations, though not likenesses, are symbols of that something; and that the part of that something, which we call the nervous system, is an apparatus for supplying us with a sort of algebra of fact, based on those symbols. A brain may be the machinery by which the material universe becomes conscious of itself. But it is important to notice that, even if this conception of the universe and of the relation of consciousness to its other components should be true, we should, nevertheless, be still bound by the limits of thought, still unable to refute the arguments of pure idealism. The more completely the materialistic position is admitted, the easier is it to show that the idealistic position is unassailable, if the idealist confines himself within the limits of positive knowledge.

Hume deals with the questions whether all our ideas are derived from experience, or whether, on the contrary, more or fewer of them are innate, which so much exercised the mind of Locke, after a somewhat summary fashion, in a note to the second section of the Inquiry:—

"It is probable that no more was meant by those who denied innate ideas, than that all ideas were copies of our impressions; though it must be confessed that the terms which they employed were not chosen with such caution, nor so exactly defined, as to prevent all mistakes about their doctrine. For what is meant by innate? If innate be equivalent to natural, then all the perceptions and ideas of the mind must be allowed to be innate or natural, in whatever sense we take the latter word, whether in opposition to what is uncommon, artificial, or miraculous. If by innate be meant contemporary with our birth, the dispute seems to be frivolous; nor is it worth while to inquire at what time thinking begins, whether before, at, or after our birth. Again, the word idea seems to be commonly taken in a very loose sense by Locke and others, as standing for any of our perceptions, our sensations and passions, as well as thoughts. Now in this sense I should desire to know what can be meant by asserting that self-love, or resentment of injuries, or the passion between the sexes is not innate?

"But admitting these terms, impressions and ideas, in the sense above explained, and understanding by innate what is original or copied from no precedent perception, then we may assert that all our impressions are innate, and our ideas not innate."

It would seem that Hume did not think it worth while to acquire a comprehension of the real points at issue in the controversy which he thus carelessly dismisses.

Yet Descartes has defined what he means by innate ideas with so much precision, that misconception ought to have been impossible. He says that, when he speaks of an idea being "innate," he means that it exists potentially in the mind, before it is actually called into existence by whatever is its appropriate exciting cause.

"I have never either thought or said," he writes, "that the mind has any need of innate ideas [idees naturelles] which are anything distinct from its faculty of thinking. But it is true that observing that there are certain thoughts which arise neither from external objects nor from the determination of my will, but only from my faculty of thinking; in order to mark the difference between the ideas or the notions which are the forms of these thoughts, and to distinguish them from the others, which may be called extraneous or voluntary, I have called them innate. But I have used this term in the same sense as when we say that generosity is innate in certain families; or that certain maladies, such as gout or gravel, are innate in others; not that children born in these families are troubled with such diseases in their mother's womb; but because they are born with the disposition or the faculty of contracting them."[22]

His troublesome disciple, Regius, having asserted that all our ideas come from observation or tradition, Descartes remarks:—

"So thoroughly erroneous is this assertion, that whoever has a proper comprehension of the action of our senses, and understands precisely the nature of that which is transmitted by them to our thinking faculty, will rather affirm that no ideas of things, such as are formed in thought, are brought to us by the senses, so that there is nothing in our ideas which is other than innate in the mind (naturel a l'esprit), or in the faculty of thinking, if only certain circumstances are excepted, which belong only to experience. For example, it is experience alone which causes us to judge that such and such ideas, now present in our minds, are related to certain things which are external to us; not in truth, that they have been sent into our mind by these things, such as they are, by the organs of the senses; but because these organs have transmitted something which has occasioned the mind, in virtue of its innate power, to form them at this time rather than at another....

"Nothing passes from external objects to the soul except certain motions of matter (mouvemens corporels), but neither these motions, nor the figures which they produce, are conceived by us as they exist in the sensory organs, as I have fully explained in my "Dioptrics"; whence it follows that even the ideas of motion and of figures are innate (naturellement en nous). And, a fortiori, the ideas of pain, of colours, of sounds, and of all similar things must be innate, in order that the mind may represent them to itself, on the occasion of certain motions of matter with which they have no resemblance."

Whoever denies what is, in fact, an inconceivable proposition, that sensations pass, as such, from the external world into the mind, must admit the conclusion here laid down by Descartes, that, strictly speaking, sensations, and a fortiori, all the other contents of the mind, are innate. Or, to state the matter in accordance with the views previously expounded, that they are products of the inherent properties of the thinking organ, in which they lie potentially, before they are called into existence by their appropriate causes.

But if all the contents of the mind are innate, what is meant by experience?

It is the conversion, by unknown causes, of these innate potentialities into actual existences. The organ of thought, prior to experience, may be compared to an untouched piano, in which it may be properly said that music is innate, inasmuch as its mechanism contains, potentially, so many octaves of musical notes. The unknown cause of sensation which Descartes calls the "je ne sais quoi dans les objets" or "choses telles qu'elles sont," and Kant the "Noumenon" or "Ding an sich," is represented by the musician; who, by touching the keys, converts the potentiality of the mechanism into actual sounds. A note so produced is the equivalent of a single experience.

All the melodies and harmonies that proceed from the piano depend upon the action of the musician upon the keys. There is no internal mechanism which, when certain keys are struck, gives rise to an accompaniment of which the musician is only indirectly the cause. According to Descartes, however—and this is what is generally fixed upon as the essence of his doctrine of innate ideas—the mind possesses such an internal mechanism, by which certain classes of thoughts are generated, on the occasion of certain experiences. Such thoughts are innate, just as sensations are innate; they are not copies of sensations, any more than sensations are copies of motions; they are invariably generated in the mind, when certain experiences arise in it, just as sensations are invariably generated when certain bodily motions take place; they are universal, inasmuch as they arise under the same conditions in all men; they are necessary, because their genesis under these conditions is invariable. These innate thoughts are what Descartes terms "verites" or truths: that is beliefs—and his notions respecting them are plainly set forth in a passage of the Principes.

"Thus far I have discussed that which we know as things: it remains that I should speak of that which we know as truths. For example, when we think that it is impossible to make anything out of nothing, we do not imagine that this proposition is a thing which exists, or a property of something, but we take it for a certain eternal truth, which has its seat in the mind (pensee), and is called a common notion or an axiom. Similarly, when we affirm that it is impossible that one and the same thing should exist and not exist at the same time; that that which has been created should not have been created; that he who thinks must exist while he thinks; and a number of other like propositions; these are only truths, and not things which exist outside our thoughts. And there is such a number of these that it would be wearisome to enumerate them: nor is it necessary to do so, because we cannot fail to know them when the occasion of thinking about them presents itself, and we are not blinded by any prejudices."

It would appear that Locke was not more familiar with Descartes' writings than Hume seems to have been; for, viewed in relation to the passages just cited, the arguments adduced in his famous polemic against innate ideas are totally irrelevant.

It has been shown that Hume practically, if not in so many words, admits the justice of Descartes' assertion that, strictly speaking, sensations are innate; that is to say, that they are the product of the reaction of the organ of the mind on the stimulus of an "unknown cause," which is Descartes' "je ne sais quoi." Therefore, the difference between Descartes' opinion and that of Hume resolves itself into this: Given sensation-experiences, can all the contents of consciousness be derived from the collocation and metamorphosis of these experiences? Or, are new elements of consciousness, products of an innate potentiality distinct from sensibility, added to these? Hume affirms the former position, Descartes the latter. If the analysis of the phenomena of consciousness given in the preceding pages is correct, Hume is in error; while the father of modern philosophy had a truer insight, though he overstated the case. For want of sufficiently searching psychological investigations, Descartes was led to suppose that innumerable ideas, the evolution of which in the course of experience can be demonstrated, were direct or innate products of the thinking faculty.

As has been already pointed out, it is the great merit of Kant that he started afresh on the track indicated by Descartes, and steadily upheld the doctrine of the existence of elements of consciousness, which are neither sense-experiences nor any modifications of them. We may demur to the expression that space and time are forms of sensory intuition; but it imperfectly represents the great fact that co-existence and succession are mental phenomena not given in the mere sense experience.[23]

FOOTNOTES:

[22] Remarques de Rene Descartes sur un certain placard imprime aux Pays Bas vers la fin de l'annee, 1647.—Descartes, OEuvres. Ed. Cousin, x. p. 71.

[23] "Wir koennen uns keinen Gegenstand denken, ohne durch Kategorien; wir koennen keinen gedachten Gegenstand erkennen, ohne durch Anschauungen, die jenen Begriffen entsprechen. Nun sind alle unsere Anschauungen sinnlich, und diese Erkenntniss, so fern der Gegenstand derselben gegeben ist, ist empirisch. Empirische Erkenntniss aber ist Erfahrung. Folglich ist uns keine Erkenntniss a priori moeglich, als lediglich von Gegenstaenden moeglicher Erfahrung."

"Aber diese Erkenntniss, die bloss auf Gegenstaende der Erfahrung eingeschraenkt ist, ist darum nicht alle von der Erfahrung entlehnt, sondern was sowohl die reinen Anschauungen, als die reinen Verstandesbegriffe betrifft, so sind sie Elemente der Erkenntniss die in uns a priori angetroffen werden."—Kritik der reinen Vernunft. Elementarlehre, p. 135.

Without a glossary explanatory of Kant's terminology, this passage would be hardly intelligible in a translation; but it may be paraphrased thus: All knowledge is founded upon experiences of sensation, but it is not all derived from those experiences; inasmuch as the impressions of relation ("reine Anschauungen"; "reine Verstandesbegriffe") have a potential or a priori existence in us, and by their addition to sense-experiences, constitute knowledge.



CHAPTER IV.

THE CLASSIFICATION AND THE NOMENCLATURE OF MENTAL OPERATIONS.

If, as has been set forth in the preceding chapter, all mental states are effects of physical causes, it follows that what are called mental faculties and operations are, properly speaking, cerebral functions, allotted to definite, though not yet precisely assignable, parts of the brain.

These functions appear to be reducible to three groups, namely: Sensation, Correlation, and Ideation.

The organs of the functions of sensation and correlation are those portions of the cerebral substance, the molecular changes of which give rise to impressions of sensation and impressions of relation.

The changes in the nervous matter which bring about the effects which we call its functions, follow upon some kind of stimulus, and rapidly reaching their maximum, as rapidly die away. The effect of the irritation of a nerve-fibre on the cerebral substance with which it is connected may be compared to the pulling of a long bell-wire. The impulse takes a little time to reach the bell; the bell rings and then becomes quiescent, until another pull is given. So, in the brain, every sensation is the ring of a cerebral particle, the effect of a momentary impulse sent along a nerve-fibre.

If there were a complete likeness between the two terms of this very rough and ready comparison, it is obvious that there could be no such thing as memory. A bell records no audible sign of having been rung five minutes ago, and the activity of a sensigenous cerebral particle might similarly leave no trace. Under these circumstances, again, it would seem that the only impressions of relation which could arise would be those of co-existence and of similarity. For succession implies memory of an antecedent state.[24]

But the special peculiarity of the cerebral apparatus is, that any given function which has once been performed is very easily set a-going again, by causes more or less different from those to which it owed its origin. Of the mechanism of this generation of images of impressions or ideas (in Hume's sense), which may be termed Ideation, we know nothing at present, though the fact and its results are familiar enough.

During our waking, and many of our sleeping, hours, in fact, the function of ideation is in continual, if not continuous, activity. Trains of thought, as we call them, succeed one another without intermission, even when the starting of new trains by fresh sense-impressions is as far as possible prevented. The rapidity and the intensity of this ideational process are obviously dependent upon physiological conditions. The widest differences in these respects are constitutional in men of different temperaments; and are observable in oneself, under varying conditions of hunger and repletion, fatigue and freshness, calmness and emotional excitement. The influence of diet on dreams; of stimulants upon the fulness and the velocity of the stream of thought; the delirious phantasms generated by disease, by hashish, or by alcohol; will occur to every one as examples of the marvellous sensitiveness of the apparatus of ideation to purely physical influences.

The succession of mental states in ideation is not fortuitous, but follows the law of association, which may be stated thus: that every idea tends to be followed by some other idea which is associated with the first, or its impression, by a relation of succession, of contiguity, or of likeness.

Thus the idea of the word horse just now presented itself to my mind, and was followed in quick succession by the ideas of four legs, hoofs, teeth, rider, saddle, racing, cheating; all of which ideas are connected in my experience with the impression, or the idea, of a horse and with one another, by the relations of contiguity and succession. No great attention to what passes in the mind is needful to prove that our trains of thought are neither to be arrested, nor even permanently controlled, by our desires or emotions. Nevertheless they are largely influenced by them. In the presence of a strong desire, or emotion, the stream of thought no longer flows on in a straight course, but seems, as it were, to eddy round the idea of that which is the object of the emotion. Every one who has "eaten his bread in sorrow" knows how strangely the current of ideas whirls about the conception of the object of regret or remorse as a centre; every now and then, indeed, breaking away into the new tracks suggested by passing associations, but still returning to the central thought. Few can have been so happy as to have escaped the social bore, whose pet notion is certain to crop up whatever topic is started; while the fixed idea of the monomaniac is but the extreme form of the same phenomenon.

And as, on the one hand, it is so hard to drive away the thought we would fain be rid of; so, upon the other, the pleasant imaginations which we would so gladly retain are, sooner or later, jostled away by the crowd of claimants for birth into the world of consciousness; which hover as a sort of psychical possibilities, or inverse ghosts, the bodily presentments of spiritual phenomena to be, in the limbo of the brain. In that form of desire which is called "attention," the train of thought, held fast, for a time, in the desired direction, seems ever striving to get on to another line—and the junctions and sidings are so multitudinous!

The constituents of trains of ideas may be grouped in various ways.

Hume says:—

"We find, by experience, that when any impression has been present in the mind, it again makes its appearance there as an idea, and this it may do in two different ways: either when, on its new appearance, it retains a considerable degree of its first vivacity, and is somewhat intermediate between an impression and an idea; or when it entirely loses that vivacity, and is a perfect idea. The faculty by which we repeat our impressions in the first manner, is called the memory, and the other the imagination."—(I. pp. 23, 24.)

And he considers that the only difference between ideas of imagination and those of memory, except the superior vivacity of the latter, lies in the fact that those of memory preserve the original order of the impressions from which they are derived, while the imagination "is free to transpose and change its ideas."

The latter statement of the difference between memory and imagination is less open to cavil than the former, though by no means unassailable.

The special characteristic of a memory surely is not its vividness; but that it is a complex idea, in which the idea of that which is remembered is related by co-existence with other ideas, and by antecedence with present impressions.

If I say I remember A. B., the chance acquaintance of ten years ago, it is not because my idea of A. B. is very vivid—on the contrary, it is extremely faint—but because that idea is associated with ideas of impressions co-existent with those which I call A. B.; and that all these are at the end of the long series of ideas, which represent that much past time. In truth I have a much more vivid idea of Mr. Pickwick, or of Colonel Newcome, than I have of A. B.; but, associated with the ideas of these persons, I have no idea of their having ever been derived from the world of impressions; and so they are relegated to the world of imagination. On the other hand, the characteristic of an imagination may properly be said to lie not in its intensity, but in the fact that, as Hume puts it, "the arrangement," or the relations, of the ideas are different from those in which the impressions, whence these ideas are derived, occurred; or in other words, that the thing imagined has not happened. In popular usage, however, imagination is frequently employed for simple memory—"In imagination I was back in the old times."

It is a curious omission on Hume's part that, while thus dwelling on two classes of ideas, Memories and Imaginations, he has not, at the same time, taken notice of a third group, of no small importance, which are as different from imaginations as memories are; though, like the latter, they are often confounded with pure imaginations in general speech. These are the ideas of expectation, or as they may be called for the sake of brevity, Expectations; which differ from simple imaginations in being associated with the idea of the existence of corresponding impressions, in the future, just as memories contain the idea of the existence of the corresponding impressions in the past.

The ideas belonging to two of the three groups enumerated: namely, memories and expectations, present some features, of particular interest. And first, with respect to memories.

In Hume's words, all simple ideas are copies of simple impressions. The idea of a single sensation is a faint, but accurate, image of that sensation; the idea of a relation is a reproduction of the feeling of co-existence, of succession, or of similarity. But, when complex impressions or complex ideas are reproduced as memories, it is probable that the copies never give all the details of the originals with perfect accuracy, and it is certain that they rarely do so. No one possesses a memory so good, that if he has only once observed a natural object, a second inspection does not show him something that he has forgotten. Almost all, if not all, our memories are therefore sketches, rather than portraits, of the originals—the salient features are obvious, while the subordinate characters are obscure or unrepresented.

Now, when several complex impressions which are more or less different from one another—let us say that out of ten impressions in each, six are the same in all, and four are different from all the rest—are successively presented to the mind, it is easy to see what must be the nature of the result. The repetition of the six similar impressions will strengthen the six corresponding elements of the complex idea, which will therefore acquire greater vividness; while the four differing impressions of each will not only acquire no greater strength than they had at first, but, in accordance with the law of association, they will all tend to appear at once, and will thus neutralise one another.

This mental operation may be rendered comprehensible by considering what takes place in the formation of compound photographs—when the images of the faces of six sitters, for example, are each received on the same photographic plate, for a sixth of the time requisite to take one portrait. The final result is that all those points in which the six faces agree are brought out strongly, while all those in which they differ are left vague; and thus what may be termed a generic portrait of the six, in contradistinction to a specific portrait of any one, is produced.

Thus our ideas of single complex impressions are incomplete in one way, and those of numerous, more or less similar, complex impressions are incomplete in another way; that is to say, they are generic, not specific. And hence it follows, that our ideas of the impressions in question are not, in the strict sense of the word, copies of those impressions; while, at the same time, they may exist in the mind independently of language.

The generic ideas which are formed from several similar, but not identical, complex experiences are what are commonly called abstract or general ideas; and Berkeley endeavoured to prove that all general ideas are nothing but particular ideas annexed to a certain term, which gives them a more extensive signification, and makes them recall, upon occasion, other individuals which are similar to them. Hume says that he regards this as "one of the greatest and the most valuable discoveries that has been made of late years in the republic of letters," and endeavours to confirm it in such a manner that it shall be "put beyond all doubt and controversy."

I may venture to express a doubt whether he has succeeded in his object; but the subject is an abstruse one; and I must content myself with the remark, that though Berkeley's view appears to be largely applicable to such general ideas as are formed after language has been acquired, and to all the more abstract sort of conceptions, yet that general ideas of sensible objects may nevertheless be produced in the way indicated, and may exist independently of language. In dreams, one sees houses, trees and other objects, which are perfectly recognisable as such, but which remind one of the actual objects as seen "out of the corner of the eye," or of the pictures thrown by a badly-focussed magic lantern. A man addresses us who is like a figure seen by twilight; or we travel through countries where every feature of the scenery is vague; the outlines of the hills are ill-marked, and the rivers have no defined banks. They are, in short, generic ideas of many past impressions of men, hills, and rivers. An anatomist who occupies himself intently with the examination of several specimens of some new kind of animal, in course of time acquires so vivid a conception of its form and structure, that the idea may take visible shape and become a sort of waking dream. But the figure which thus presents itself is generic, not specific. It is no copy of any one specimen, but, more or less, a mean of the series; and there seems no reason to doubt that the minds of children before they learn to speak, and of deaf mutes, are peopled with similarly generated generic ideas of sensible objects.

It has been seen that a memory is a complex idea made up of at least two constituents. In the first place there is the idea of an object; and secondly, there is the idea of the relation of antecedence between that object and some present objects.

To say that one has a recollection of a given event and to express the belief that it happened, are two ways of giving an account of one and the same mental fact. But the former mode of stating the fact of memory is preferable, at present, because it certainly does not presuppose the existence of language in the mind of the rememberer; while it may be said that the latter does. It is perfectly possible to have the idea of an event A, and of the events B, C, D, which came between it and the present state E, as mere mental pictures. It is hardly to be doubted that children have very distinct memories long before they can speak; and we believe that such is the case because they act upon their memories. But, if they act upon their memories, they to all intents and purposes believe their memories. In other words, though, being devoid of language, the child cannot frame a proposition expressive of belief; cannot say "sugar-plum was sweet;" yet the psychical operation of which that proposition is merely the verbal expression, is perfectly effected. The experience of the co-existence of sweetness with sugar has produced a state of mind which bears the same relation to a verbal proposition, as the natural disposition to produce a given idea, assumed to exist by Descartes as an "innate idea" would bear to that idea put into words.

The fact that the beliefs of memory precede the use of language, and therefore are originally purely instinctive, and independent of any rational justification, should have been of great importance to Hume, from its bearing upon his theory of causation; and it is curious that he has not adverted to it, but always takes the trustworthiness of memories for granted. It may be worth while briefly to make good the omission.

That I was in pain, yesterday, is as certain to me as any matter of fact can be; by no effort of the imagination is it possible for me really to entertain the contrary belief. At the same time, I am bound to admit, that the whole foundation for my belief is the fact, that the idea of pain is indissolubly associated in my mind with the idea of that much past time. Any one who will be at the trouble may provide himself with hundreds of examples to the same effect.

This and similar observations are important under another aspect. They prove that the idea of even a single strong impression may be so powerfully associated with that of a certain time, as to originate a belief of which the contrary is inconceivable, and which may therefore be properly said to be necessary. A single weak, or moderately strong, impression may not be represented by any memory. But this defect of weak experiences may be compensated by their repetition; and what Hume means by "custom" or "habit" is simply the repetition of experiences.

"wherever the repetition of any particular act or operation produces a propensity to renew the same act or operation, without being impelled by any reasoning or process of the understanding, we always say that this propensity is the effect of Custom. By employing that word, we pretend not to have given the ultimate reason of such a propensity. We only point out a principle of human nature which is universally acknowledged, and which is well known by its effects."—(IV. p. 52.)

It has been shown that an expectation is a complex idea which, like a memory, is made up of two constituents. The one is the idea of an object, the other is the idea of a relation of sequence between that object and some present object; and the reasoning which applied to memories applies to expectations. To have an expectation[25] of a given event, and to believe that it will happen, are only two modes of stating the same fact. Again, just in the same way as we call a memory, put into words, a belief, so we give the same name to an expectation in like clothing. And the fact already cited, that a child before it can speak acts upon its memories, is good evidence that it forms expectations. The infant who knows the meaning neither of "sugar-plum" nor of "sweet," nevertheless is in full possession of that complex idea, which, when he has learned to employ language, will take the form of the verbal proposition, "A sugar-plum will be sweet."

Thus, beliefs of expectation, or at any rate their potentialities, are, as much as those of memory, antecedent to speech, and are as incapable of justification by any logical process. In fact, expectations are but memories inverted. The association which is the foundation of expectation must exist as a memory before it can play its part. As Hume says,—

" ... it is certain we here advance a very intelligible proposition at least, if not a true one, when we assert that after the constant conjunction of two objects, heat and flame, for instance, weight and solidity, we are determined by custom alone to expect the one from the appearance of the other. This hypothesis seems even the only one which explains the difficulty why we draw from a thousand instances, an inference which we are not able to draw from one instance, that is in no respect different from them."...

"Custom, then, is the great guide of human life. It is that principle alone which renders our experience useful to us, and makes us expect, for the future, a similar train of events with those which have appeared in the past."...

"All belief of matter-of-fact or real existence is derived merely from some object present to the memory or senses, and a customary conjunction between that and some other object; or in other words, having found, in many instances, that any two kinds of objects, flame and heat, snow and cold, have always been conjoined together: if flame or snow be presented anew to the senses, the mind is carried by custom to expect heat or cold, and to believe that such a quality does exist, and will discover itself upon a nearer approach. This belief is the necessary result of placing the mind in such circumstances. It is an operation of the soul, when we are so situated, as unavoidable as to feel the passion of love, when we receive benefits, or hatred, when we meet with injuries. All these operations are a species of natural instincts, which no reasoning or process of the thought and understanding is able either to produce or to prevent."—(IV. pp. 52-56.)

The only comment that appears needful here is, that Hume has attached somewhat too exclusive a weight to that repetition of experiences to which alone the term "custom" can be properly applied. The proverb says that "a burnt child dreads the fire"; and any one who will make the experiment will find, that one burning is quite sufficient to establish an indissoluble belief that contact with fire and pain go together.

As a sort of inverted memory, expectation follows the same laws; hence, while a belief of expectation is, in most cases, as Hume truly says, established by custom, or the repetition of weak impressions, it may quite well be based upon a single strong experience. In the absence of language, a specific memory cannot be strengthened by repetition. It is obvious that that which has happened cannot happen again, with the same collateral associations of co-existence and succession. But, memories of the co-existence and succession of impressions are capable of being indefinitely strengthened by the recurrence of similar impressions, in the same order, even though the collateral associations are totally different; in fact, the ideas of these impressions become generic.

If I recollect that a piece of ice was cold yesterday, nothing can strengthen the recollection of that particular fact; on the contrary, it may grow weaker, in the absence of any record of it. But if I touch ice to-day and again find it cold, the association is repeated, and the memory of it becomes stronger. And, by this very simple process of repetition of experience, it has become utterly impossible for us to think of having handled ice without thinking of its coldness. But, that which is, under the one aspect, the strengthening of a memory, is, under the other, the intensification of an expectation. Not only can we not think of having touched ice, without feeling cold, but we cannot think of touching ice, in the future, without expecting to feel cold. An expectation so strong that it cannot be changed, or abolished, may thus be generated out of repeated experiences. And it is important to note that such expectations may be formed quite unconsciously. In my dressing room, a certain can is usually kept full of water, and I am in the habit of lifting it to pour out water for washing. Sometimes the servant has forgotten to fill it, and then I find that, when I take hold of the handle, the can goes up with a jerk. Long association has, in fact, led me to expect the can to have a considerable weight; and, quite unawares, my muscular effort is adjusted to the expectation.

The process of strengthening generic memories of succession, and, at the same time, intensifying expectations of succession, is what is commonly called verification. The impression B has frequently been observed to follow the impression A. The association thus produced is represented as the memory, A -> B. When the impression A appears again, the idea of B follows, associated with that of the immediate appearance of the impression B. If the impression B does appear, the expectation is said to be verified; while the memory A -> B is strengthened, and gives rise in turn to a stronger expectation. And repeated verification may render that expectation so strong that its non-verification is inconceivable.

FOOTNOTES:

[24] It is not worth while, for the present purpose, to consider whether, as all nervous action occupies a sensible time, the duration of one impression might not overlap that of the impression which follows it, in the case supposed.

[25] We give no name to faint memories; but expectations of like character play so large a part in human affairs that they, together with the associated emotions of pleasure and pain, are distinguished as "hopes" or "fears."



CHAPTER V.

THE MENTAL PHENOMENA OF ANIMALS.

In the course of the preceding chapters, attention has been more than once called to the fact, that the elements of consciousness and the operations of the mental faculties, under discussion, exist independently of and antecedent to, the existence of language.

If any weight is to be attached to arguments from analogy, there is overwhelming evidence in favour of the belief that children, before they can speak, and deaf mutes, possess the feelings to which those who have acquired the faculty of speech apply the name of sensations; that they have the feelings of relation; that trains of ideas pass through their minds; that generic ideas are formed from specific ones; and, that among these, ideas of memory and expectation occupy a most important place, inasmuch as, in their quality of potential beliefs, they furnish the grounds of action. This conclusion, in truth, is one of those which, though they cannot be demonstrated, are never doubted; and, since it is highly probable and cannot be disproved, we are quite safe in accepting it, as, at any rate, a good working hypothesis.

But, if we accept it, we must extend it to a much wider assemblage of living beings. Whatever cogency is attached to the arguments in favour of the occurrence of all the fundamental phenomena of mind in young children and deaf mutes, an equal force must be allowed to appertain to those which may be adduced to prove that the higher animals have minds. We must admit that Hume does not express himself too strongly when he says—

"no truth appears to me more evident, than that the beasts are endowed with thought and reason as well as men. The arguments are in this case so obvious, that they never escape the most stupid and ignorant."—(I. p. 232.)

In fact, this is one of the few cases in which the conviction which forces itself upon the stupid and the ignorant, is fortified by the reasonings of the intelligent, and has its foundation deepened by every increase of knowledge. It is not merely that the observation of the actions of animals almost irresistibly suggests the attribution to them of mental states, such as those which accompany corresponding actions in men. The minute comparison which has been instituted by anatomists and physiologists between the organs which we know to constitute the apparatus of thought in man, and the corresponding organs in brutes, has demonstrated the existence of the closest similarity between the two, not only in structure, as far as the microscope will carry us, but in function, as far as functions are determinable by experiment. There is no question in the mind of any one acquainted with the facts that, so far as observation and experiment can take us, the structure and the functions of the nervous system are fundamentally the same in an ape, or in a dog, and in a man. And the suggestion that we must stop at the exact point at which direct proof fails us; and refuse to believe that the similarity which extends so far stretches yet further, is no better than a quibble. Robinson Crusoe did not feel bound to conclude, from the single human footprint which he saw in the sand, that the maker of the impression had only one leg.