In the study of Nature, either mental or physical, the aim of the scientific enquirer is to diminish as much as possible the catalogue of ultimate truths. When, without doing violence to facts, he is able to bring one phenomenon within the laws of another; when he can shew that a fact or agency, which seemed to be original and distinct, could have been produced by other known facts and agencies, acting according to their own laws; the enquirer who has arrived at this result, considers himself to have made an important advance in the knowledge of nature, and to have brought science, in that department, a step nearer to perfection. Other accessions to science, however important practically, are, in a scientific point of view, mere additions to the materials: this is something done towards perfecting the structure itself.
The manner in which this scientific improvement takes place is by the resolution of phenomena which are special and complex into others more general and simple. Two cases of this sort may be roughly distinguished, though the distinction between them will not be found on accurate examination to be fundamental. In one case it is the order of the phenomena that is analysed and simplified; in the other it is the phenomena themselves. When the observed facts relating to the weight of terrestrial objects, and those relating to the motion of the heavenly bodies, were found to conform to one and the same law, that of the gravitation of every particle of matter to every other particle with a force varying as the inverse square of the distance, this was an example of the first kind. The order of the phenomena was resolved into a more general law. A great number of the successions which take place in the material world were shewn to be particular cases of a law of causation pervading all Nature. The other class of investigations are those which deal, not with the successions of phenomena, but with the complex phenomena themselves, and disclose to us that the very fact which we are studying is made up of simpler facts: as when the substance Water was found to be an actual compound of two other bodies, hydrogen and oxygen; substances very unlike itself, but both actually present in every one of its particles. By processes like those employed in this case, all the variety of substances which meet our senses and compose the planet on which we live, have been shewn to be constituted by the intimate union, in a certain number of fixed proportions, of some two or more of sixty or seventy bodies, called Elements or Simple Substances, by which is only meant that they have not hitherto been found capable of further decomposition. This last process is known by the name of chemical analysis: but the first mentioned, of which the Newtonian generalization is the most perfect type, is no less analytical. The difference is, that the one analyses substances into simpler substances; the other, laws into simpler laws. The one is partly a physical operation; the other is wholly intellectual.
Both these processes are as largely applicable, and as much required, in the investigation of mental phenomena as of material. And in the one case as in the other, the advance of scientific knowledge may be measured by the progress made in resolving complex facts into simpler ones.
The phenomena of the Mind include multitudes of facts, of an extraordinary degree of complexity. By observing them one at a time with sufficient care, it is possible in the mental, as it is in the material world, to obtain empirical generalizations of limited compass, but of great value for practice. When, however, we find it possible to connect many of these detached generalizations together, by discovering the more general laws of which they are cases, and to the operation of which in some particular sets of circumstances they are due, we gain not only a scientific, but a practical advantage; for we then first learn how far we can rely on the more limited generalizations; within what conditions their truth is confined; by what changes of circumstances they would be defeated or modified.
Not only is the order in which the more complex mental phenomena follow or accompany one another, reducible, by an analysis similar in kind to the Newtonian, to a comparatively small number of laws of succession among simpler facts, connected as cause and effect; but the phenomena themselves can mostly be shewn, by an analysis resembling those of chemistry, to be made up of simpler phenomena. “In the mind of man,” says Dr. Thomas Brown, in one of his Introductory Lectures, “all is in a state of constant and ever-varying complexity, and a single sentiment may be the slow result of innumerable feelings. There is not a single pleasure, or pain, or thought, or emotion, that may not, by the influence of that associating principle which is afterwards to come under our consideration, be so connected with other pleasures, or pains, or thoughts, or emotions, as to form with them, for ever after, an union the most intimate. The complex, or seemingly complex, phenomena of thought, which result from the constant operation of this principle of the mind, it is the labour of the intellectual inquirer to analyse, as it is the labour of the chemist to reduce the compound bodies on which he operates, however close and intimate their combination may be, to their constituent elements.... From the very instant of its first existence, the mind is constantly exhibiting phenomena more and more complex: sensations, thoughts, emotions, all mingling together, and almost every feeling modifying, in some greater or less degree, the feelings that succeed it; and as, in chemistry, it often happens that the qualities of the separate ingredients of a compound body are not recognizable by us in the apparently different qualities of the compound itself, — so in this spontaneous chemistry of the mind, the compound sentiment that results from the association of former feelings has, in many cases, on first consideration, so little resemblance to these constituents of it, as formerly existing in their elementary state, that it requires the most attentive reflection to separate, and evolve distinctly to others, the assemblages which even a few years may have produced. It is, therefore, scarcely possible to advance even a single step, in intellectual physics, without the necessity of performing some sort of analysis, by which we reduce to simpler elements some complex feeling that seems to us virtually to involve them.”
These explanations define and characterize the task which was proposed to himself by the author of the present treatise, and which he concisely expressed by naming his work an Analysis of the Phenomena of the Human Mind. It is an attempt to reach the simplest elements which by their combination generate the manifold complexity of our mental states, and to assign the laws of those elements, and the elementary laws of their combination, from which laws, the subordinate ones which govern the compound states are consequences and corollaries.
The conception of the problem did not, of course, originate with the author; he merely applied to mental science the idea of scientific inquiry which had been matured by the successful pursuit, for many generations, of the knowledge of external nature. Even in the particular path by which he endeavoured to reach the end, he had eminent precursors. The analytic study of the facts of the human mind began with Aristotle; it was first carried to a considerable height by Hobbes and Locke, who are the real founders of that view of the Mind which regards the greater part of its intellectual structure as having been built up by Experience. These three philosophers have all left their names identified with the great fundamental law of Association of Ideas; yet none of them saw far enough to perceive that it is through this law that Experience operates in moulding our thoughts and forming our thinking powers. Dr. Hartley was the man of genius who first clearly discerned that this is the key to the explanation of the more complex mental phenomena, though he, too, was indebted for the original conjecture to another wise forgotten thinker, Mr. Gay. Dr. Hartley’s treatise (“Observations on Man”) goes over the whole field of the mental phenomena, both intellectual and emotional, and points out the way in which, as he thinks, sensations, ideas of sensation, and association, generate and account for the principal complications of our mental nature. If this doctrine is destined to be accepted as, in the main, the true theory of the Mind, to Hartley will always belong the glory of having originated it. But his book made scarcely any impression upon the thought of his age. He incumbered his theory of Association with a premature hypothesis respecting the physical mechanism of sensation and thought; and even had he not done so, his mode of exposition was little calculated to make any converts but such as were capable of working out the system for themselves from a few hints. His book is made up of hints rather than of proofs. It is like the production of a thinker who has carried his doctrines so long in his mind without communicating them, that he has become accustomed to leap over many of the intermediate links necessary for enabling other persons to reach his conclusions, and who, when at last he sits down to write, is unable to recover them. It was another great disadvantage to Hartley’s theory, that its publication so nearly coincided with the commencement of the reaction against the Experience psychology, provoked by the hardy scepticism of Hume. From these various causes, though the philosophy of Hartley never died out, having been kept alive by Priestley, the elder Darwin, and their pupils, it was generally neglected, until at length the author of the present work gave it an importance that it can never again lose. One distinguished thinker, Dr. Thomas Brown, regarded some of the mental phenomena from a point of view similar to Hartley’s, and all that he did for psychology was in this direction; but he had read Hartley’s work either very superficially, or not at all: he seems to have derived nothing from it, and though he made some successful analyses of mental phenomena by means of the laws of association, he rejected, or ignored, the more searching applications of those laws; resting content, when he arrived at the more difficult problems, with mere verbal generalizations, such as his futile explanations by what he termed “relative suggestion.” Brown’s psychology was no outcome of Hartley’s; it must be classed as an original but feebler effort in a somewhat similar direction.
It is to the author of the present volumes that the honour belongs of being the reviver and second founder of the Association psychology. Great as is this merit, it was but one among many services which he rendered to his generation and to mankind. When the literary and philosophical history of this century comes to be written as it deserves to be, very few are the names figuring in it to whom as high a place will be awarded as to James Mill. In the vigour and penetration of his intellect he has had few superiors in the history of thought: in the wide compass of the human interests which he cared for and served, he was almost equally remarkable: and the energy and determination of his character, giving effect to as single-minded an ardour for the improvement of mankind and of human life as I believe has ever existed, make his life a memorable example. All his work as a thinker was devoted to the service of mankind, either by the direct improvement of their beliefs and sentiments, or by warring against the various influences which he regarded as obstacles to their progress: and while he put as much conscientious thought and labour into everything he did, as if he had never done anything else, the subjects on which he wrote took as wide a range as if he had written without any labour at all. That the same man should have been the author of the History of India and of the present treatise, is of itself sufficiently significant. The former of those works, which by most men would have been thought a sufficient achievement for a whole literary life, may be said without exaggeration to have been the commencement of rational thinking on the subject of India: and by that, and his subsequent labours as an administrator of Indian interests under the East India Company, he effected a great amount of good, and laid the foundation of much more, to the many millions of Asiatics for whose bad or good government his country is responsible. The same great work is full of far-reaching ideas on the practical interests of the world; and while forming an important chapter in the history and philosophy of civilization (a subject which had not then been so scientifically studied as it has been since) it is one of the most valuable contributions yet made even to the English history of the period it embraces. If, in addition to the History and to the present treatise, all the author’s minor writings were collected; the outline treatises on nearly all the great branches of moral and political science which he drew up for the Supplement to the Encyclopædia Britannica, and his countless contributions to many periodical works; although advanced thinkers have outgrown some of his opinions, and include, on many subjects, in their speculations, a wider range of considerations than his, every one would be astonished at the variety of his topics, and the abundance of the knowledge he exhibited respecting them all. One of his minor services was, that he was the first to put together in a compact and systematic form, and in a manner, adapted to learners, the principles of Political Economy as renovated by the genius of Ricardo: whose great work, it may be mentioned by the way, would probably never have seen the light, if his intimate and attached friend Mr. Mill had not encouraged and urged him, first to commit to paper his profound thoughts, and afterwards to send them forth to the world. Many other cases might be mentioned in which Mr. Mill’s private and personal influence was a means of doing good, hardly inferior to his public exertions. Though, like all who value their time for higher purposes, he went little into what is called society, he helped, encouraged, and not seldom prompted, many of the men who were most useful in their generation: from his obscure privacy he was during many years of his life the soul of what is now called the advanced Liberal party; and such was the effect of his conversation, and of the tone of his character, on those who were within reach of its influence, that many, then young, who have since made themselves honoured in the world by a valuable career, look back to their intercourse with him as having had a considerable share in deciding their course through life. The most distinguished of them all, Mr. Grote, has put on record, in a recent publication, his sense of these obligations, in terms equally honourable to both. As a converser, Mr. Mill has had few equals; as an argumentative converser, in modern tunes probably none. All his mental resources seemed to be at his command at any moment, and were then freely employed in removing difficulties which in his writings for the public he often did not think it worth while to notice. To a logical acumen which has always been acknowledged, he united a clear appreciation of the practical side of things, for which he did not always receive credit from those who had no personal knowledge of him, but which made a deep impression on those who were acquainted with the official correspondence of the East India Company conducted by him. The moral qualities which shone in his conversation were, if possible, more valuable to those who had the privilege of sharing it, than even the intellectual. They were precisely such as young men of cultivated intellect, with good aspirations but a character not yet thoroughly formed, are likely to derive most benefit from. A deeply rooted trust in the general progress of the human race, joined with a good sense which made him never build unreasonable or exaggerated hopes on any one event or contingency; an habitual estimate of men according to their real worth as sources of good to their fellow-creatures, and an unaffected contempt for the weaknesses or temptations that divert them from that object, making those with whom he conversed feel how painful it would be to them to be counted by him among such backsliders; a sustained earnestness, in which neither vanity nor personal ambition had any part, and which spread from him by a sympathetic contagion to those who had sufficient moral preparation to value and seek the opportunity; this was the mixture of qualities which made his conversation almost unrivalled in its salutary moral effect. He has been accused of asperity, and there was asperity in some few of his writings; but no party spirit, personal rivalry, or wounded amour-propre ever stirred it up. Even when he had received direct personal offence, he was the most placable of men. The bitterest and ablest attack ever publicly made on him was that which was the immediate cause of the introduction of Mr. Macaulay into public life. He felt it keenly at the time, but with a quite impersonal feeling, as he would have felt any thing that he thought unjustly said against any opinion or cause which was dear to him; and within a very few years afterwards he was on terms of personal friendship with its author, as Lord Macaulay himself, in a very creditable passage of the preface to his collected Essays, has, in feeling terms, commemorated.
At an early period of Mr. Mill’s philosophical life, Hartley’s work had taken a strong hold of his mind; and in the maturity of his powers he formed and executed the purpose of following up Hartley’s leading thought, and completing what that thinker had begun. The result was the present work, which is not only an immense advance on Hartley’s in the qualities which facilitate the access of recondite thoughts to minds to which they are new, but attains an elevation far beyond Hartley’s in the thoughts themselves. Compared with it, Hartley’s is little more than a sketch, though an eminently suggestive one: often rather showing where to seek for the explanation of the more complex mental phenomena, than actually explaining them. The present treatise makes clear, much that Hartley left obscure: it possesses the great secret for clearness, though a secret commonly neglected — it bestows an extra amount of explanation and exemplification on the most elementary parts. It analyses many important mental phenomena which Hartley passed over, and analyses more completely and satisfactorily most of those of which he commenced the analysis. In particular, the author was the first who fully understood and expounded (though the germs of this as of all the rest of the theory are in Hartley) the remarkable case of Inseparable Association: and inasmuch as many of the more difficult analyses of the mental phenomena can only be performed by the aid of that doctrine, much had been left for him to analyse.
I am far from thinking that the more recondite specimens of analysis in this work are always successful, or that the author has not left something to be corrected as well as much to be completed by his successors. The completion has been especially the work of two distinguished thinkers in the present generation, Professor Bain and Mr. Herbert Spencer; in the writings of both of whom, the Association Psychology has reached a still higher development. The former of these has favoured me with his invaluable collaboration in annotating the present work. In the annotations it has been our object not only to illustrate and enforce, but to criticise, where criticism seemed called for. What there is in the work that seems to need correction, arises chiefly from two causes. First, the imperfection of physiological science at the time at which it was written, and the much greater knowledge since acquired of the functions of our nervous organism and their relations with the mental operations. Secondly, an opening was made for some mistakes, and occasional insufficiency of analysis, by a mental quality which the author exhibits not unfrequently in his speculations, though as a practical thinker both on public and on private matters it was quite otherwise; a certain impatience of detail. The bent of his mind was towards that, in which also his greatest strength lay; in seizing the larger features of a subject — the commanding laws which govern and connect many phenomena. Having reached these, he sometimes gives himself up to the current of thoughts which those comprehensive laws suggest, not stopping to guard himself carefully in the minutiæ of their application, nor devoting much of his thoughts to anticipating all the objections that could be made, though the necessity of replying to some of them might have led him to detect imperfections in his analyses. From this cause (as it appears to me), he has occasionally gone further in the pursuit of simplification, and in the reduction of the more recondite mental phenomena to the more elementary, than I am able to follow him; and has left some of his opinions open to objections, which he has not afforded the means of answering. When this appeared to Mr. Bain or myself to be the case, we have made such attempts as we were able to place the matter in a clearer light; and one or other, or both, have supplied what our own investigations or those of others have provided, towards correcting any shortcomings in the theory.
Mr. Findlater, of Edinburgh, Editor of Chambers’ Cyclopædia, has kindly communicated, from the rich stores of his philological knowledge, the corrections required by the somewhat obsolete philology which the author had borrowed from Horne Tooke. For the rectification of an erroneous statement respecting the relation of the Aristotelian doctrine of General Ideas to the Platonic, and for some other contributions in which historical is combined with philosophical interest, I am indebted to the illustrious historian of Greece and of the Greek philosophy. Mr. Grote’s, Mr. Bain’s and Mr. Findlater’s notes are distinguished by their initials; my own, as those of the Editor.
The question presented itself, whether the annotations would be most useful, collected at the end of the work, or appended to the chapters or passages to which they more particularly relate. Either plan has its recommendations, but those of the course which I have adopted seemed to me on the whole to preponderate. The reader can, if he thinks fit, (and, if he is a real student, I venture to recommend that he should do so) combine the advantages of both modes, by giving a first careful reading to the book itself, or at all events to every successive chapter of the book, without paying any attention to the annotations. No other mode of proceeding will give perfectly fair play to the author, whose thoughts will in this manner have as full an opportunity of impressing themselves on the mind, without having their consecutiveness broken in upon by any other person’s thoughts, as they would have had if simply republished without comment. When the student has done all he can with the author’s own exposition — has possessed himself of the ideas, and felt, perhaps, some of the difficulties, he will be in a better position for profiting by any aid that the notes may afford, and will be in less danger of accepting, without due examination, the opinion of the last comer as the best.
“I shall inquire into the original of those ideas, notions, or whatever else you please to call them, which a man observes and is conscious to himself he has in his mind; and the ways whereby the understanding comes to be furnished with them.”
Locke, i. 1, 3.
Philosophical inquiries into the human mind have for their main, and ultimate object, the exposition of its more complex phenomena.
It is necessary, however, that the simple should be premised; because they are the elements of which the complex are formed; and because a distinct knowledge of the elements is indispensable to an accurate conception of that which is compounded of them.
The feelings which we have through the external senses are the most simple, at least the most familiar, of the mental phenomena. Hence the propriety of commencing with this class of our feelings.
“I shall not at present meddle with the physical consideration of the mind, or trouble myself to examine wherein its essence consists; or by what motions of our spirits, or alterations of our bodies, we come to have any Sensation by our organs, or any Ideas in our understandings; and whether those ideas do in their formation, any or all of them, depend on matter or no. These are speculations which, however curious and entertaining, I shall decline, as lying out of my way in the design I am now upon.” — Locke, i. 1, 2.
My object, in what I shall say respecting the phenomena classed under the head of Sensation, is, to lead such of my readers as are new to this species of inquiry to conceive the feelings distinctly. All men are familiar with them; but this very familiarity, as the mind runs easily from one well known object to another, is a reason why the boundary between them and other feelings is not always observed. It is necessary, therefore, that the learner should by practice acquire the habit of reflecting upon his Sensations, as a distinct class of feelings; and should be hence prepared to mark well the distinction between them and other states of mind, when he advances to the analysis of the more mysterious phenomena.
What we commonly mean, when we use the terms Sensation or phenomena of Sensation, are the feelings which we have by the five senses, — Smell, Taste, Hearing, Touch, and Sight. These are the feelings from which we derive our notions of what we denominate the external world; — the things by which we are surrounded: that is, the antecedents of the most interesting consequents, in the whole series of feelings, which constitute our mental train, or existence.
The feelings, however, which belong to the five external Senses are not a full enumeration of the feelings which it seems proper to rank under the head of Sensations, and which must be considered as bearing an important part in those complicated phenomena, which it is our principal business, in this inquiry, to separate into their principal elements, and explain. Of these unnamed, and generally unregarded, Sensations, two principal classes may be distinguished: — first, Those which accompany the action of the several muscles of the body; and, secondly, Those which have their place in the Alimentary Canal.
It is not material to the present purpose in what order we survey the subdivisions of this elementary class of the mental phenomena. It will be convenient to take those first, which can be most easily thought of by themselves; that is, of which a conception, free from the mixture of any extraneous ingredient, can be most certainly formed. For this reason we begin with Smell.
These three distinguishable particulars are common to all the five Senses. With regard to the Organ, which is a physical rather than a mental subject of inquiry, I shall have occasion to say little more than is required to make my reader distinguish, with sufficient accuracy, the part of his body to which the separate feelings of his five Senses belong. And with regard to the antecedent of the Sensation, or Object of the Senses, the proper place for explaining what is capable of being known of it is at a subsequent part of this inquiry. My desire at present is, to fix the attention of the reader upon the Sensation; that he may mark it as a mental state of a particular kind, distinct from every other feeling of his nature.
The Organ of Smell, as every body knows, is situated in the mouth and nostrils, or in the nerves, appropriated to smelling, which are found in the passage between the mouth and nostrils, and in the vicinity of that passage.
Though it appears to be ascertained that the nerves are necessary to sensation, it is by no means ascertained in what way they become necessary. It is a mystery how the nerves, similar in all parts of the body, afford us, in one place, the sensation of sound; in another, the sensations of light and colours; in another, those of odours, in another those of flavours, and tastes, and so on.
With respect to the external Object, as it is usually denominated, of this particular sense; in other words, the antecedent, of which the Sensation Smell is the consequent; it is, in vulgar apprehension, the visible, tangible object, from which the odour proceeds. Thus, we are said to smell a rose, when we have the sensation derived from the odour of the rose. It is more correct language, however, to say, that we smell the odorous particles which proceed from the visible, tangible object, than that we smell the object itself; for, if any thing prevents the odorous particles, which the body emits, from reaching the organ of smell, the sensation is not obtained. The object of the sense of smelling then are odorous particles, which only operate, or produce the sensation, when they reach the organ of smell.
But what is meant by odorous particles we are still in ignorance. Something, neither visible nor tangible, is conveyed, through the air, to the olfactory nerves; but of this something we know no more than that it is the antecedent of that nervous change, or variety of consciousness, which we denote by the word smell.
Still farther, When we say that the odorous particles, of which we are thus ignorant, reach the nerves which constitute the organ of smell, we attach hardly any meaning to the word reach. We know not whether the particles in question produce their effect, by contact, or without contact. As the nerves in every part of the body are covered, we know not how any external particles can reach them. We know not whether such particles operate upon the nerves, by their own, or by any other influence; the galvanic, for example, or electrical, influence.
These observations, with regard to the organ of smell, and the object of smell, are of importance, chiefly as they show us how imperfect our knowledge still is of all that is merely corporeal in sensation, and enable us to fix our attention more exclusively upon that which alone is material to our subsequent inquiries — that point of consciousness which we denominate the sensation of smell, the mere feeling, detached from every thing else.
When we smell a rose, there is a particular feeling, a particular consciousness, distinct from all others, which we mean to denote, when we call it the smell of the rose. In like manner we speak of the smell of hay, the smell of turpentine, and the smell of a fox. We also speak of good smells, and bad smells; meaning by the one, those which are agreeable to us; by the other, those which are offensive. In all these cases what we speak of is a point of consciousness, a thing which we can describe no otherwise than by calling it a feeling; a part of that series, that succession, that flow of something, on account of which we call ourselves living or sensitive creatures.
We can distinguish this feeling, this consciousness, the sensation of smell, from every other sensation. Smell and Sound are two very different things; so are smell and sight. The smell of a rose is different from the colour of the rose; it is also different from the smoothness of the rose, or the sensation we have by touching the rose.
We not only distinguish the sensations of smell from those of the other senses, but we distinguish the sensations of smell from one another. The smell of a rose is one sensation; the smell of a violet is another. The difference we find between one smell and another is in some cases very great; between the smell of a rose, for example, and that of carrion or assafœtida.
The number of distinguishable smells is very great. Almost every object in nature has a peculiar smell; every animal, every plant, and almost every mineral. Not only have the different classes of objects different smells, but probably different individuals in the same class. The different smells of different individuals are perceptible, to a certain extent, even by the human organs, and to a much greater extent by those of the dog, and other animals, whose sense of smelling is more acute.
We can conceive ourselves, as endowed with smelling, and not enjoying any other faculty. In that case, we should have no idea of objects as seeable, as hearable, as touchable, or tasteable. We should have a train of smells; the smell at one time of the rose, at another of the violet, at another of carrion, and so on. The successive points of consciousness, composing our sentient being, would be mere smells. Our life would be a train of smells, and nothing more. Smell, and Life, would be two names for the same thing.
The terms which our language supplies, for speaking of this sense, are exceedingly imperfect. It would obviously be desirable to have, at any rate, distinct names for the Organ, for the Object, and for the Sensation; and that these names should never be confounded. It happens, unfortunately, that the word Smell is applicable to all the three. That the word smell expresses, both the quality, as we vulgarly say, of the object smelt; and also the feeling of him by whom it is smelt, every one is aware. If you ask whether the smell, when I hold a violet to my nostrils, is in me or in the violet, it would be perfectly proper to say, in both. The same thing, however, is not in both, though the two things have the same name. What is in me is the sensation, the feeling, the point of consciousness; and that can be in nothing but a sentient being. What is in the rose, is what I call a quality of the rose; in fact, the antecedent of my sensation; of which, beside its being the antecedent of my sensation, I know nothing. If I were speaking of a place in which my senses had been variously affected, and should say, that, along with other pleasures, I had enjoyed a succession of the most delightful smells, I should be understood to speak of my sensations. If I were speaking of a number of unknown objects, and should say of one, that it had a smell like that of honey; of another, that it had a smell like that of garlick; I should be understood as speaking of the object of each sensation, a quality of the thing smelt.
In the phrases in which smell is called a Sense, as when we say, that smell is one of the five senses, there is considerable complexity. The term here imports the organ, it imports the sensation, and, in a certain way, it imports also the object. It imports the organ as existing continuously, the sensation as existing only under a certain condition, and that condition the presence of the object.
In Hearing, the same three particulars, the Organ, the Object, and the Feeling, require to be distinguished.
The name of the organ is the Ear; and its nice and complicated structure has been described with minuteness and admiration by anatomists and physiologists.
In vulgar discourse, the object of our Sense of Hearing is a sounding body. We say that we hear the bell, the trumpet, the cannon. This language, however, is not correct. That which precedes the feeling received through the ear, is the approach of vibrating air to the ear. Certain bodies, made to vibrate in a certain way, communicate vibrations to the air, and the vibrating air, admitted into the ear, is followed by the sensation of hearing. If the air which the body makes to vibrate does not enter the ear, however the body itself may vibrate, sensation does not follow; hearing does not take place. There is, in fact, no sound. Of the circumstances in which sound is generated, part only were present. There was the organ, and there was the object, but not that juxta-position which is needed to make the antecedent of the sensation complete. Air vibrating in juxta-position to the organ, is the object of Hearing.
How air in vibration should produce the remarkable effect, called hearing, in the nerves of the ear, and no effect in those of the eye, in those of smelling, or those of taste, our knowledge does not enable us to tell.
It is not very difficult to think of the sensation of hearing, apart from the organ, and from the object, as well as from every other feeling. I hear the hum of bees. The feeling to which I give this name is a point of my own consciousness; it is an elementary part of my sensitive being; of that thread of consciousness, drawn out in succession, which I call myself. I have the hearing; it is a sensation of my own; it is my feeling, and no other man’s feeling; it is a very different feeling from taste, and a very different feeling from smell, and from all my other feelings.