"Seasons return; but not to me returnsDay, or the sweet approach of even or morn."
"Seasons return; but not to me returnsDay, or the sweet approach of even or morn."
§ V.—Amount of Information Derived from the Respective Senses
A further Question as to one Class of the Senses.—The relations and specific functions of the several senses have been already described. Some further questions arise, however, respecting the precise amount and kind of information afforded by that class of the senses which; as wehave seen, relates to the spatial properties of bodies, in distinction from the chemical, viz.: hearing, sight, and touch.
What is given in Hearing.—And first, as to the sense ofhearing. What is it precisely that we hear? When we listen to a sound, we speak of hearing the object that produces the sound; we say, I hear a bell, a bird, a gun, etc. Strictly speaking, we do not hear the object, but only the sound. It is not the bell or the bird that we hear, but the vibration of the air produced by bell and bird. This has been already illustrated by reference to a carriage passing in the street. It is only by experience, aided by other senses, that we learn to refer the sound to its producing cause.
Hearing not properly Perception.—Is hearing then a sensation merely, or is it a perception? If by perception we mean a direct knowledge of the external object—which is the proper sense of the word—hearing certainly is not perception. It gives us no such immediate knowledge. What we perceive in hearing is merely the sensation of sound. It may be doubted whether by this sense alone we should ever get the idea that what we hear is any thing external to ourselves.
Affords the means of Judging.—As it is, however, we judge, not only of the existence and nature, but of the distance and direction of the external object whence the sound proceeds. We learn to do this with great correctness, and with great facility. No sooner do we hear a sound, in most instances, than we form an opinion at once, from what direction it comes, and what produces it; nor are we often mistaken in our judgment. The faculty of judging by the ear as to the direction of the sound, and the nature of the object producing it, may be cultivated by care and practice to a remarkable degree of accuracy. Napoleon was seldom mistaken as to the direction and distance of a cannonade. It is said that the Indian of the north-western prairies by applying his ear to the ground, will detect the approach of a body of cavalry at a distance beyond thereach of vision, and distinguish their tread from that of a herd of buffaloes.
Number of Sounds.—The number of sounds which the ear can distinguish is almost without limit. There are, it is said, five hundred distinct tones which an ear of usual accuracy can recognize, and each of these tones admits of five hundred variations of loudness, giving, in all, two hundred and fifty thousand different sounds.
Power of Sound over the Mind.—The power of sound to affect the mind, and especially the feelings, is too well known to require specific statement. The note of an instrument, the tone of a human voice, the wild warbling of a bird, the tinkling of a bell, the variations of speech and of song, from the high and shrill to the low and heavy intonation, from the quick and impetuous to the slow and plaintive movement, these simple varieties of tone affect powerfully the heart, and find their way at once and irresistibly to the feelings. Hence the power of music over even the uncultivated mind; hence too in no small degree the power of the skilful orator over the feelings of his audience. It is not merely, nor so much, the thing said, in many cases, as the way of saying it, that touches and sways the assembled multitude. Tones and sounds have a natural meaning. They are the natural language of the heart. They express emotion, and hence awaken emotions in others.
The Question as to Sight.—Turning now from the sense ofhearingto that ofsight, the question arises, What is it precisely that we perceive by the eye? When we fix the eye upon any object, more or less remote, what is it, strictly speaking, that we see, extension and figure, or only color? Is it by vision that we learn primarily the distance of objects and their locality? These are points requiring investigation.
Does Sight give Extension and Figure.—As to the first of these questions, whether extension and figure are objects of direct visual perception. No doubt they are associatedin our minds with the act of vision, so that the moment we see an object we obtain an idea of it as extended, and of such and such dimensions and figure. The question is, whether it is really through the sense of sight that we obtain this idea, or in some other way. Had we no other means of information, would sight alone give us this? When we first open our eyes on external objects, do we receive the idea of extension and figure, or only of color? The fact that as matters are, we cannot in our experience separate the notion of some surface extension from the sensation of color, is not decisive of these questions. We cannot, as Dr. Brown observes, separate the color from the convexity and magnitude of an oak before us, but this does not prove that convexity and magnitude are objects of immediate and original perception. If every surface in nature had been convex, suggests the same writer, we should probably have found the same difficulty in attempting to conceive of color as separate from convexity, that we now find in attempting to conceive of it as separate from length and breadth. As it is, however, our sensation of color has not always been associated with convexity, while it has been always associated with surface extension. Hence it is, he maintains, that we seem to perceive, by the eye, the length, and breadth, and objects along with their color.
Argument from the Affection of a Portion of the Retina.—The fact that in vision a certain portion of the retina in length and breadth is actually affected by the light falling on it, has been supposed by some to be conclusive of the fact that we perceive the length and breadth of the external object by the eye. This does not necessarily follow. As Dr. Brown contends, it is equally true that a certain part of the organ of smell is affected by odors, and a certain part of the auditory nerve is affected by sounds, yet we are not conscious of any perception of extension by either of these organs; we neither smell nor hear the length, and breadth, and magnitude of objects; nor is there any reason to supposethat the particular portion of the retina affected has any thing to do with the original sensation of sight.
Amount of the preceding Arguments.—These arguments however, do not strike me as conclusive. They merely show thepossibilitythat extension and figuremay beacquired rather than original perceptions. They do not amount to positive evidence that theyareso.
An Argument to the Contrary.—On the other hand, there is one consideration of a positive character, which to most minds will be likely to outweigh the merely negative arguments already adduced. Color is a property of light, and light comes to us reflected from objects occupying space; we perceive it only as we perceive it spread over and reflected from some surface. Extension, then, surface expansion of the reflecting object, is the indispensable condition of the visibility of light itself, and so of color, as reflected from the object. Now it is difficult to persuade ourselves that what we know to be an essential condition of the perception of color, and what we seem to perceive along with the color, and cannot, even in thought, wholly separate from it, is not, after all, really perceived by the eye.
Argument from recent Discoveries.—Indeed, recent discoveries in science seem to vindicate that not only surface extension, but trinal extension, orsolidity, may be an object of direct perception by the eye. I refer to the researches of Wheatstone, in binocular vision, which go to show, that in consequence of the difference of the images formed upon the right and the left eye, as occupying different positions with reference to the object seen, we are enabled by the eye to cognize the solidity as well as the extension of objects. The difference of figure in the two images gives us this. That such is the case is shown by an instrument, the stereoscope, so constructed as to present separately the image as formed on each eye, which, when separately viewed, appear as mere plane surfaces, but when viewed together, the right image with the right eye, andthe left one with the left eye, at the same time, present no longer the appearance of plane surfaces, but the two images combine to form one distinct figure, and that a solid, having length, breadth, thickness, and standing out with all the semblance of the real object.
It is hardly necessary to say that if extension is an object of perception by the eye, so also is figure, which is merely thelimitationof extension in different directions.
Second Question—Does Sight give Distance?—Is it also by vision that we obtain the idea of thedistanceof objects and their externality? Does vision alone give the idea that what we see is numerically distinct from ourselves, and that it occupies this or that particular locality? So it would seem, judging from the impression left upon the mind in the act of vision. We seem to see the object as here or there, external, more or less distant in space. We distinguish it from ourselves.
The negative View.—This is denied by some. All that we see, they contend, is merely the light coming from the object, and from the variations and modifications which this exhibits we learn to judge by experience of the distance and locality of the object. It is a matter of judgment and not of perception. We have learned to associate the two things, the visual appearance and the distance.
Argument in the Negative.—In proof of this they adduce the fact that we are frequently mistaken in our estimate of the distance of objects. If there be more or fewer intervening objects than usual, if the atmosphere be more or less clear than usual, or any like circumstance affords a variation from our ordinary experience, we are misled as to the distance of the object. Hence we mistake the distance of ships at sea, or of objects on a prairie or a desert, the width of rivers, the height of steeples, towers, etc.
Further Argument in the Negative.—It is further contended that facts show that the impressions of sight alone, uncorrected by experience, do not convey the idea ofdistance at all, but that what we see seems to be in connection with the eye itself, until we learn the contrary by the aid of other senses. This, it is said, is the experience of persons who have been operated upon for cataract, particularly of a patient whose case is described by Cheselden, and who thought every thing which he saw, touched his eyes. It is said also to have been the same with Caspar Hauser, when first liberated from the long confinement of his dungeon, and permitted to look out upon the external world. The goodly landscape seemed to him to be a group of figures, drawn upon the window.
Force of this Argument.—This, however, is not inconsistent with the perception of externality by vision, since even what seems to be in contact with the eye, nay, what is known to be so, may still be known as external. Contact implies externality. It is very much to be doubted, moreover, whether the cases now referred to, coincide with the usual experience of those who are learning to see. The little child seems to recognize the externality and remoteness from his own person of the objects which attract his attention, as soon as he learns to observe surrounding objects at all, and, though he may not judge correctly of their relative distance from himself, never seems by his movements to suppose that they are in contact with his eye or with any part of his person. The young of animals, also, as soon as they are born, seem to perceive by the eye, the externality, the direction, and the distance of objects, and govern their movements accordingly. It is not, in these cases, a matter of experience, but of direct perception. These facts render it doubtful, to say the least, whether the common impression—that which in spite of all arguments to the contrary, is, and always will be made upon the mind in the act of vision, viz., that we see objects as external, as having locality, and as more or less remote from us—is not, after all, the correct impression.
Learning to judge of Distance not inconsistent with thisView.—- Nor does it conflict with this view that we learn to judge of the true distance of objects, and are often deceived in regard to it. Themeasurementof distance, the more or less of it, is of course a matter of experience, a thing to be learned by practice. It does not follow, however, that we may not by the eye directly, and at first, perceive an object to be external, and removed from us, in other words distant, though we may not know at firsthowdistant. The rays of light that come to us from this external object, may give us direct perception of the object as external, as extended, and as occupying apparently a given locality in space more or less remote, while at the same time it may be left to other senses and to experience to determine how great that distance is.
Questions as to Touch.—Passing now from the sense of sight to that oftouch, we find similar questions discussed among philosophers respecting the precise information afforded by this sense. Does touch give us immediate perception of externality, extension, form, hardness, softness, etc., including the various mechanical properties of bodies? To this sense it has been common to ascribe these faculties of perception. They are so attributed by Reid, Upham, Wayland, and, I believe, by modern writers generally, with the exception of Brown and Hamilton.
Probability of another Source of Information.—It may be questioned, I think, whether, as regards some of these qualities at least, it is not rather the consciousness of resistance to muscular effort, than the sense of touch, properly speaking, that is the informing source. So, for example, as to hardness; the application of an external body lightly to the hand awakens the sense of touch, but conveys no idea of hardness. Let the same object be allowed to rest with gradually increasing weight upon the hand until it becomes painful, and we get the idea of weight, gravitation, but not of the hardness or impenetrability of the object. It is only when our muscular effort to move or penetrate the externalbody is met and resisted by the same, that we learn the impenetrability of the opposing body.
Other Perceptions attributable to the same Source.—So with regard to externality, extension, and form. When an external object, a cube, for example, or an ivory ball, is placed on the palm of the hand, sensation is awakened, but is that sensation necessarily accompanied with the perception of the external object as such? Does the mere tactual sensation, in the first instance, and of itself, inform us that there is something external to ourselves, that what we feel is not a part of our own organism? We are conscious of a change in the sensation of the part affected, but are we immediately conscious that this change is produced by something external? Let there be given, however, the consciousness of resistance to our muscular movements, as when the cube or ball, for instance, prevents the effort to close the hand, or when our locomotion is impeded by the presence of some obstacle, and will not the same resistance inform us of the extension of the resisting body, and so of its form and figure? We learn whereabout in space this resistance occurs, and where it ceases. The tactual sensation would indeed very soon come to our aid in this cognition, and serve as a guiding sense, even in the absence of the former. The question is, whether this alone would, in the first instance, give us such cognitions?
Our first Ideas of Extension, how derived.—We have had reference in this discussion only to the qualities ofexternalbodies. There can be little question that ourfirstideas of extension are derived from our own sentient organism, the consciousness of sensations in different parts of the body, distinct from, and out of each other, thus affording the knowledge of an extended sentient organization. The idea of externality, or outness, and extension, thus acquired, the transition is easy from the perception of our own bodies as possessing these qualities, to the cognizance of the same qualities in external objects.
§ VI.—Credibility of our Sensations and Perceptions.
Denied by some.—There have always been those who were disposed to call in question the testimony of the senses. Such were the Eleatics and the Skeptics among the Greek philosophers, and there have not been wanting among the moderns minds of acuteness and ingenuity that have followed in the same path. While admitting thephenomenaof sense, theappearanceof things as being so and so, they have called in question the corresponding objective reality. Things appear to me to be thus and thus—such and such impressions are made on my senses—that I cannot deny; but how do I know that the reality corresponds to my impressions, or, in fact, that there is any reality? How know we our senses to be reliable? What evidence have we that they do not habitually deceive us?
Evidence demanded.—It were perhaps a sufficient answer to this question to reply, Whatevidencehave we, or can we have, that theydodeceive us? In the absence of all evidence to the contrary, is it not more reasonable to suppose that our perceptions correspond to realities, than that they are without foundation, uncaused, or caused by something not at all answering to the apparent object of perception; more reasonable to suppose that there is a real table or book answering to my perception of one, than that I have the perception while there is no such reality? It remains with those, then, who question and deny the validity of sense-perception, to show reasons for such denial. And this becomes the more imperative on them, inasmuch as they contradict the common belief and universal opinion of mankind—nay, what, in spite of all their arguments, is still, by their own confession, their own practical conviction and belief.
Evidence impossible.—But whence is this evidence to come? Where is it to be sought? How are we to prove that sense deceives us, except by arguments drawn from sense? And if sense is not reliable in the first instance,why rely upon it in the second, to prove that it is not reliable? If the senses do habitually deceive us, manifestly it can never be shown that they do. And, even if this could be shown, it would be impossible to find any thing better to rely upon in their stead. We have these guides or none. We have these instruments of observation provided for the voyage of life. We may pronounce them worthless and throw them into the sea, but we cannot replace them.
Inconsistent and contradictory Testimony of Sense.—But it may be replied that the testimony of sense is often inconsistent with itself, and contradictory of itself. What is sweet to one is sour and bitter to another. What seems a round tower in the distance becomes a square one as you approach; and the straight stick that you hold in your hand appears crooked when thrust into the water. There is in reality, however, no contradiction or inconsistency in the cases supposed. The change of circumstances accounts in every instance for the change of appearance. In the case of the stick, for example, the different density of the water accounts for the refraction of the rays of light that pass through it, and this accounts for the crooked appearance of the stick that is only partially submerged. So in the other cases; it is no contradiction that an object which appears round at a distance of ten miles, should appear square at the distance of so many rods—or that the taste of two persons should not agree as to the savor of a given object.
Deceptions of Sense.—It may be further objected that in certain states of the physical organism, sensations are experienced which seem to be of external origin, but are really produced by internal changes; and that in such cases we have the same perceptions, see the same objects, hear the same things, that we should if there were a corresponding external reality, while nevertheless there is no such reality, and it can be proved that there is none. If this may happen in some cases, why not in others, or in all?
Reply.—I reply, the simple fact, that in the casesupposed the deception can be detected and proved, shows the difference between that and ordinary perception. If the senses were not habitually reliable, we could not detect the mistake in this particular instance. If all coin were counterfeit, how could we detect a counterfeit coin? We know, moreover, how to account for the mistake in the case before us. It occurs, by the supposition, only in a certain state of the organism, that is, only in a diseased, abnormal condition of the system. The exception proves the rule.
Distinction of direct and indirect Testimony.—A distinction is to be made, in the discussion of this subject, between the direct and indirect testimony of the senses, between that which is strictly and properly perception, and that which is only conception, judgment, inference. What I really perceive, for example, in the case of the distant tower, or the stick partially under water, is only a given appearance; Iinferfrom that appearance that the tower is round and the stick crooked, and in that inference I am mistaken. My judgment is at fault here, and not my senses. They testified truly and correctly. They gave the real appearance, and this was all they could give, all they ever give. This has been well stated by Dr. Reid, and, long before him, the same ground was taken, in reply to the same objection, by Aristotle and also by Epicurus.
Direct Perception gives what.—In regard to direct and immediate perception, the case is different. Here the testimony is positive to the existence of the object. When something resists my voluntary movement, I am conscious of that resistance, conscious of something external and resisting. I cannot deny the fact of that consciousness. I may, however, deny the correctness, the truthfulness of what consciousness affirms. To do this, however, is to put an end to all reasoning on the subject, for, when we give up consciousness as no longer reliable, there is nothing left to fall back upon. If any one chooses to leap from this precipice, we can only sayfinis.
§ VII.—HISTORICAL SKETCH.
I.Of Different Divisions of the Qualities of Bodies.
The Greek Philosophers.—The distinction of the qualities of bodies into two classes, differing in important respects, is by no means a modern one. It was recognized by some of the earlier Greek philosophers, who held that the sweet, bitter, hot, cold, etc., are rather affections of our own senses than proper qualities of matter, having independent existence. Subsequently the view was adopted by Protagoras, and by the Cyrenean and Epicurean schools. Plato held it, and especially and very fully, Aristotle, who calls the qualities to which we have referred, and which are usually denominated secondary,affectivequalities, because they have the power of affecting the senses, while the qualities now usually termed primary, as extension, figure, motion, number, etc., he regards as not properly objects of sense. The former class he calls proper sensibles, the latter, common.
The Schoolmen.—Theschoolmenmade much of this distinction, and held, with Aristotle, that the qualities now called primary, require, for their cognition, other faculties than those of sense.
Doctrine of Galileo.—Galileopoints out the true ground and philosophy of this distinction, and also gives the nameprimaryto the class referred to, viz.,those qualities which are necessary to our conception of body, as for example, figure, size, place, etc., while, on the contrary, colors, tastes, etc., are not inherent in bodies, but only in us, and we can conceive of body without them. The former are real qualities of bodies, while the latter are only conceptions which give us no real knowledge of any thing external, but only of the affections of our own minds.
The Moderns.—DescartesandLockemerely adopted these distinctions as they found them, without essential modification. So also didReidandStewart, although bothincluded among the primary qualities some which are properly secondary, as roughness, smoothness, hardness, softness. Indeed Stewart restricted the primary qualities to those and such as those just named.
Hamilton.—No writer has so fully elaborated this matter as Sir William Hamilton, to whom we are indebted mainly for the historical facts now stated, and whose dissertations are and must ever remain an invaluable thesaurus on the philosophy of perception. So complete and elaborate is his classification of the qualities of matter, that I shall be pardoned for giving a synopsis of its principal points in this connection.
Hamilton's Scheme—General Divisions.—He divides the qualities of bodies into three classes, which he calls primary, secundo-primary, and secondary. The primary are thought as essential to the very notion of matter, and may be deducedà priori, the bare notion of matter being given; while the secundo-primary and the secondary, being accidental and contingent, must be deducedà posteriori, learned by experience. His deduction of the primary qualities is as follows:
Primary Qualities.—We can conceive of body only as, I. Occupying space; II. Contained in space. Space is a necessary form of thought, but we are not obliged to conceive of space as occupied, that is, to conceive of matter. When conceived it must be under the conditions now named.
I. The property of occupying space isSimple Solidity, which implies,a.Trinal extension, or length, breadth, and thickness;b.Impenetrability, or the property of not being reduced to non-extension. Trinal extension involves, 1. Number, or Divisibility; 2. Size, including Density; 3. Shape.
II. The attribute of being contained in space, affords the notion, 1. Of Mobility; 2. Of Position.
The essential and necessary constituents then of ournotion of matter are, 1. Extension (comprising under it, 2. Divisibility; 3. Size; 4. Density; 5. Figure); 6. Ultimate Incompressibility; 7. Mobility; 8. Situation. These are the primary qualities, products, in a sort, of the understanding, developing themselves with rigid necessity out of the given notion of substance occupying space.
Secundo-Primary Qualities.—The secundo-primary are contingent modifications of the primary, all have relation to space, and motion in space,all are contained under the category of resistance, orpressure, all are learned or included as results of experience, all have both an objective and subjective phase, being at once qualities of matter, and also affections of our senses.
Considered as to thesourcesof resistance, there is, I. That ofCo-attraction, under the forms ofa, Gravity,b, Cohesion; II. That of Repulsion; III. Inertia; all which are capable of minute subdivision. Thus from cohesion follow the hard and soft, firm and fluid, tough and brittle, rigid and flexible, rough and smooth, etc., etc. From repulsion are derived compressible and incompressible, resilient and irresilient.
Secondary Qualities.—The secondary qualities are, as apprehended by us, not properly attributes of body at all, but only affections of our nervous organism. They belong to bodies only so far as these are furnished with the power of exciting our nervous organism to the specific action thus designated. To this class belong color, sound, flavor, savor, tactile sensation, feeling of heat, electricity, etc. Such also are titillation, sneezing, shuddering, and the various sensations, pleasurable or painful, resulting from the action of external stimuli.
These Classes further distinguished.—Of the qualities thus derived, the primary are known immediately in themselves, the secondary only mediately in their effects on us, the secundo-primary both immediately in themselves, and mediately in their effects on us. The primary are qualities of body in relation to body simply, and to our organismas such; the secundo-primary are qualities of body in relation to our organism, not as body in general, but as body of a particular sort, viz.: propelling, resisting, cohesive; the secondary are qualities of body in relation to our organism as excitable and sentient. The primary may be roundly characterized as mathematical, the secundo-primary as mechanical, the secondary as physiological.
Reasons for retaining the twofold Division.—Such, in brief outline, are the principal points of Hamilton's classification. While following in the main the distinctions here indicated, I have preferred to retain the old division into primary and secondary, as at once more simple, and sufficiently accurate, merely dividing the secondary into two classes, the mechanical (secundo-primary of Hamilton), and physiological. We are thus enabled, not merely to retain a division and nomenclature which have antiquity and authority in their favor, and are well-nigh universally received, but we avoid the almost barbarous terminology of Sir William's classification—while, at the same time, we indicate with sufficient precision the important distinction between the so-called secundo-primary and secondary qualities.
II.Of Different Theories of Perception.
Realists and Idealists.—There are two leading theories, quite distinct from each other, which have widely prevailed, and divided the thinking world, as to the philosophy of perception. The one maintains that in perception we havedirect cognizanceof a real external world. This is the view taken in the preceding pages, and now generally held by psychologists in this country, and to some extent in Europe But for a long period, the prevalent, and in fact, until the time of Reid in Scotland, and Kant in Germany, the almost universally-received opinion was the reverse of this—that in perception, as in any and all other mental acts, the mind is conscious only of its own ideas, cognizant of itself and its own states only, incapable, in fact, of knowing any thingexternal to itself. Those who hold the former view are termedRealists, the latterIdealists.
Further division of the latter.—The latter, however, are of two classes. TheAbsolute Idealistshold that the notion we have of external things is purely subjective, having no external counterpart, no corresponding outward reality. In distinction from this the greater part maintain that while we are cognizant, directly and strictly, of nothing beyond our own minds, nevertheless there is an external reality corresponding to the idea in our minds, and which that idea represents. Hence they have been designatedRepresentative Idealists, or, as Sir William Hamilton terms them, Cosmothetic Idealists.
Further Distinction.—Of these latter, again, some hold the idea which we have of an external world to be merely a state or modification of the mind itself; others regard it as a sort of intermediate connecting link between mind and matter. The former may be called egoistic, and the latter non-egoistic.
Summary of Classes.—We have then these three great classes—theNatural Realists, theAbsolute Idealists, and theRepresentative Idealistscomprising the Egoistic and Non-Egoistic divisions.
Distinguished Writers of the different Classes.—On the roll of absolute idealism are names of no small distinction: Berkley and Hume, in England, Fichte and Hegel, in Germany, are of the number; while among the representative idealists one finds Descartes, Arnauld, Malebranche, Leibnitz, Locke, in fine, the greater number of philosophic writers from Descartes onward to the time of Reid. Subsequently even, we find a writer of no less repute than Dr. Brown assuming, as the basis of his philosophy of perception, the exploded theory of representative idealism, under the egoistic form. Of natural realists since the time of Reid, Sir W. Hamilton is the most distinguished.
Origin of Representative Idealism.—The doctrine ofrepresentative perception doubtless originated in the difficulty of conceiving how a purely spiritual existence, the human mind, can, by any possibility, take cognizance of, or be affected by, a purely material substance, the external world. The soul seated in its presence-chamber, the brain, can cognize nothing beyond and without, for nothing can get except where it is present. It must be, then, said the philosophers, that in order to the mind's perceiving any thing of that which lies beyond and without its own immediate locality, there must come to the mind from that outer world certain little images bearing some resemblance to the things without, andrepresentingto the soul that external world. These images—more refined than matter, less spiritual than mind itself, of an intermediate nature between the two—they termed ideas.
Tendency of Representative to Absolute Idealism.—It is easy to see how such a doctrine would lead almost inevitably toabsolute idealism. If we do not in perception take cognizance directly of matter external, but only of certain images or ideas in our own minds, then how do we know that these imagescorrectly representthe external reality, which we have never cognized, and never shall? How do we know, in fact, that thereisany such external reality? What evidence have we, in a word, of the existence of any thing beyond and without our own minds? This was the actual result to which Berkley and Hume drove the then prevalent philosophy of Europe, as to a legitimate and inevitable result.
Relation of Dr. Reid to this Controversy.—To Dr. Reid belongs the credit of rescuing philosophy from this dangerous extreme, by showing the utter falsity of the ideal theory. He took the ground that the existence of any such representative images in the mind is wholly without proof, nay more, is inconceivable; that while we can conceive of an image of form or figure, we cannot conceive of an image of sound, or of taste or smell. The hypothesis is whollywithout foundation. But even if it were conceivable and established by sufficient evidence, still it would explain nothing as to the manner in which the mind perceives external objects. It relieves no difficulty. If the representative image be itself material, how can the mind take cognizance of it? If not material, how can it represent matter, and how can the mind know that it does represent correctly the external object?
State of the Matter since Reid.—Since the time of Dr. Reid, this theory of representative perception, at least in this non-egoistic form, has been for the most part abandoned, and philosophers have been content to take the ground indicated by consciousness, and the common sense of mankind, that in perception we take direct cognizance of the external object.
Position of Hamilton.—It remained for Sir W. Hamilton to complete the work which Dr. Reid began, by showing that the representative theory, in its finer or egoistic form, as held by Dr. Brown and others, is equally untenable or unsound; that it makes little difference whether we regard the image or idea, which we take to represent the external object, as something distinct from the mind itself, or whether we view it as a mere modification or state of the mind, so long as we make any thing of the sort the direct object of perception instead of the real external thing. Idealism is the result in either case, and philosophical skepticism the goal. In place of any and all such views, Hamilton maintains, with great power and earnestness, the doctrine of natural realism—that in perception we are cognizant immediately and directly of the external object.
As no other writer has so fully elaborated this department of science, it may be of service to present in this connection the chief points of his theory.
Chief Points of Hamilton's Theory of Perception.—All perception is immediate cognition; we perceive only what we apprehend as now and here existent; and hencewhat we perceive is either in our own organism, viewed as material, extended, etc., or else is in immediate correlation to it. The organism is, in perception, viewed as not-me; in sensation, as of the me.
What is given in Perception proper.—What we apprehend in perception proper is: 1. The primary qualities of body as pertaining to our own organism; 2. The secundo-primary qualities of bodies in correlation to it. (See Hamilton's division of qualities of bodies, as above.)
Primary Qualities of external Objects, how known.—The primary qualities of things external to our organism we do not perceive immediately, but only infer, from the effects produced on us by them. Neither in perception nor sensation do we apprehend immediately, or in itself, the external cause of our affection or sensation. That is always unknown to consciousness, known only by inference or conjecture.
External Existence, how learned.—The existence of the world without is apprehended not in a perception of the primary qualities of things external, but of the secundo-primary—i. e., in the consciousness that our movements are resisted by something external to our organism. This involves the consciousness of something external, resisting. The two things are conjunctly apprehended.
This presupposes what.—This experience presupposes the notion of space, and motion in space. These are inherent, instinctive native elements of thought, and it is idle to inquire how we come by them. Every perception of sensationsout of, and distinct from, other sensations gives occasion for conceiving the idea of space.Outnessinvolves it.
Points of Difference between this Theory and Reid's.—The system, as thus stated, differs in some respects materially from the doctrine of perception advanced by Dr. Reid, and generally adopted since his time by the English and Scotch philosophers. According to Hamilton, perception is not, as held by Reid and others, theconceptionof an objectsuggestedby sensation, but the direct cognition of something.We do not merelyconceiveof the object as existing, andbelieveit to exist, weknowit andperceiveit to exist. Nor does sensation precede, and perception follow, as generally stated, but the two are, in time, conjunct, coëxistent. Nor do we perceive the secondary qualities of bodies, as such, but onlyinferthem from our sensations. Neither do we perceive distant objects through a medium, as usually held, but what we perceive is either the organism itself, as affected thus and thus, or what is directly in contact with it, as affecting and resisting it. Extension and externality, again, are not first learned bytouch, as Reid holds, and most subsequent writers, both English and American, but in other ways; the former, by the perception of the primary qualities of our own organism, as the seat of sensations distinct from other sensations elsewhere localized; the latter, by the resistance which we experience to our own locomotive force. Finally, sensation proper is not, as with Reid and others, an affection purely of the mind, but of mind and body as complex. Its subject is as much one as the other.
Nature of this Power—Its various Forms.—It is in the mind's power to conceive or represent to itself an object not at the time present to the senses. This may take place in several forms. There may be the simple reproduction in thought of the absent object of sense. There may be, along with the reproduction or recurrence of the object, therecognitionof it as a former object of sensation or perception. There may be the reproduction of the object not as it is, or was, when formerly perceived, but with variations, the different elements arranged and combined not according to the actual and original, but according to the mind's own ideals, and at its will. This latter form of conception is what is usually termed imagination—while the general term memory, as ordinarily employed, is made to include the two former. While using the term in this general sense, we may properly distinguish, however, between mental reproduction, and mental recognition, the latter being strictly the office of memory.
All these are but so many forms of the representative power. We may designate them respectively as thereproductive,recognitive, andcreativefaculties. The mind's activity is essentially the same under each of these forms. The object is notgivenbutthought, not presented to sense, butrepresentedto the mind. The process is reflective rather than intuitive. It is a matter ofunderstandingrather than ofsenseor ofreason. It is a conception, not a perception or an intuition, and it is a simple conception of the object as it is or is conceived to be, in itself considered, and not in relation to other objects.
MEMORY.
§ I.—Mental Reproduction.
I.Nature of the Process.
General Character.—As now defined, this is that form of mental activity in which the mind's former perceptions and sensations are reproduced in thought. The external objects are no longer present—the original sensations and perceptions have vanished—but by the mind's own power are reproduced to thought, giving, as it were, a representation or image of the original.
Example.—Suppose, for instance, that I have seen Strasburg minster, or the cathedral of Milan. Months, perhaps years pass away. By-and-by, in some other and remote part of the world, something reminds me of that splendid structure; I see again its imposing front, its lofty towers, its airy pinnacles and turrets. The solemn pile rises complete, as by magic, to the mind's eye, and, regardless of time or distance, the faculty of simple conception reproduces the object as it is.
Conceptions of Sound.—In like manner I form a conception, more or less distinct, of sounds once heard. The chanting of the evening service in the Church of the Madeleine at Paris, and the prolonged note of a shepherd's horn among the Alps, are instances of musical sound that frequently recur with startling distinctness to the mind.The same is to some extent true of the sensations and perceptions derived from the other senses. With more or less vividness the objects of all such sensations and perceptions are capable of being reproduced in conception.
The Conceptions not of Necessity connected with the Recollection of Self as the Percipient.—In these cases there may or may not be a connection of the object, as it lies before our minds, with our own personal history as the former percipients of that object. The time, place, circumstance, of that perception may not be distinctly before us; even the fact that we have ourselves seen, heard, felt, what we now conceive, may not, at the moment, be an object of thought. These are the elements of memory or mental recognition, and are certainly very likely to stand associated in our minds with the conception of the object itself. But not always nor of necessity is it so. There may be simple conception of the object, mental reproduction, where there is, for the time being, no recognition of any thing further. The Strasburg minster, the chanting of the choir, the note of the mountain horn, the snowy peak of Jungfrau, may stand out by themselves before the mind, abstracted from all thought of the time, the place, the circumstances in which they were originally perceived, or even from all thought of the fact that we have at some former time actually perceived these very objects. They may present themselves as pure conceptions.
Conceptions vary in some Respects.—Our conceptions vary in respect to definiteness and clearness. The objects of some of the senses are more readily and also more distinctly conceived than those of others. The sense of sight is peculiar in this respect. A visible object is more easily and more distinctly conceived than a particular sound or taste. The sense of hearing is, perhaps, next to that of sight in this respect; while the sensations of taste and smell are so seldom the objects of distinct conception, that some have even denied the power of conceiving them. Dr. Waylandmaintains this view. That we do form conceptions more or less distinct of the objects both of taste and smell, as,e. g.of the taste of a melon, or the smell of an orange, hardly admits of question; while, at the same time, it is doubtless true that we have less occasion to reproduce in thought the objects now referred to than those of sight and hearing, that they are recalled with less facility, and also with less distinctness.
Stewart's Theory.—Dugald Stewart has ingeniously suggested that the reason why a sound or a taste is less readily conceived than an object of sight, may be that the former are single detached sensations, while visible objects are complex, presenting a series of connected points of observation, and our conception of them as a whole is the result of many single conceptions, a result to which the association of ideas largely contributes. We more readily conceive two things in connection than either of them separately. On the same principle a series of sounds in a strain of music is more readily conceived than a single detached note.
Importance of this Power.—The value of this power to the mind is inestimable. Without it, the passing moment, the impression or sensation of the instant, would be the sum total of our intellectual life, of our conscious being. The horizon of our mental vision would extend no further than our immediate present perceptions. The past would be a blank as dark and uncertain even as the future. Conception lights up the otherwise dreary waste of past existence, and reproducing the former scenes and objects, gives us mental possession of all that we have been, as well as of the present moment, and lays at our feet the objects of all former knowledge. The mind thus becomes in a measure independent of sense and the external world. What it has once seen, heard, felt, becomes its permanent acquisition, even when the original object of perception is for ever removed. I may have seen the grand and stately minster, or the snowy Alp but once in all my life, but ever after it dwellsamong my conceptions, and in after years, on other continents, and amid far other scenes, that vision of beauty and grandeur passes before me as an angelic vision; that succession of sweet sounds traverses again the silent chambers of the brain, with all the freshness of first reality. It is only a conception now, but who shall estimate the worth of that simple power of conception?
The Talent for Description as affected by this Power.—The following remarks of Mr. Stewart illustrate happily one of the many uses to which this power is subservient:
"A talent for lively description, at least in the case of sensible objects, depends chiefly on the degree in which the describer possesses the power of conception. We may remark, even in common conversation, a striking difference among individuals in this respect. One man, in attempting to convey a notion of any object he has seen, seems to place it before him, and to paint from actual perception; another, although not deficient in a ready elocution, finds himself, in such a situation, confused and embarrassed among a number of particulars imperfectly apprehended, which crowd into his mind without any just order and connection. Nor is it merely to the accuracy of our descriptions that this power is subservient; it contributes, more than any thing else, to render them striking and expressive to others, by guiding us to a selection of such circumstances as are most prominent and characteristic; insomuch that I think it may reasonably be doubted if a person would not write a happier description of an object from the conception than from the perception of it. It has often been remarked, that the perfection of description does not consist in a minute specification of circumstances, but in a judicious selection of them and that the best rule for making the selection is to attend to the particulars that make the deepest impression on our own minds. When the object is actually before us, it is extremely difficult to compare the impressions which different circumstances produce; and the very thought of writinga description, would prevent the impressions which would otherwise take place. When we afterward conceive the object, the representation of it we form to ourselves, however lively, is merely an outline, and is made up of those circumstances which really struck us most at the moment, while others of less importance are obliterated."
Conceptions often Complex.—It is to be further remarked respecting the power now under consideration, that the notion, or conception which we form of an object, by means of this faculty, is frequently complex. The particular perceptions and sensations formerly experienced, and now represented, are combined, forming thus a notion of the object as a whole. The figure, magnitude, color, and various other properties, of any object, as,e. g., a table, are objects each of distinct and separate cognition, and as such are mentally reproduced, distinctly, and separately; but when thus reproduced, are combined to form the complete conception of the table, as it lies in my mind. The notion or conception of the object as a whole being thus once formed, any single perception as,e. g., of color, figure, etc., is afterward sufficient to recall and represent the whole.
Often passes for Perception.—It was remarked, in treating of perception, that very much which passes under that name is in reality only conception. I hear, for example, a carriage passing in the street. All that I really perceive is the sound; but that single perception recalls at once the various perceptions that have formerly been associated with it, and so there is at once reproduced in my mind theconceptionof the passing carriage. Our conviction of the existence and reality of the object thus conceived, is hardly inferior to that produced by actual and complete perception.
Correctness of our Conceptions.—In general it may be remarked, that our conceptions are more or less adequate and correct representations of the objects to which they relate, according as they combine the reports of more orfewer different senses, respecting more or fewer different qualities, and as these reports are more or less clear and distinct.
II.Laws of Mental Reproduction.
Conceptions not uncaused.—It is evident that our conceptions arise not uncaused and at hap-hazard, but according to some law. There is a method about the phenomena of mental reproduction. There is a reason why any particular scene or event of former experience, any perception or sensation, is brought again to mind, when it is, and as it is, rather than some other in its place. A careful observation and study of the laws which regulate in general the succession of thought, will furnish the explanation and true philosophy of mental reproduction.
Principle of Suggestion.—Every thought which passes through the mind is directly or indirectly connected with, and suggested by something which preceded; and that something may be either a sensation, a perception, a conception, or an emotion. The precedence may be either immediate or remote. Some connection there always is between any given thought or feeling at any moment before the mind, and some preceding thought or feeling, which gives rise to, occasions, suggests, the latter. These suggestions follow certain general rules or laws, which are usually called thelaws of association. These laws, so called, are only the different circumstances under which the suggestions take place, and are termed laws only to indicate the regularity and uniformity with which, under given circumstances given thoughts and feelings are awakened in the mind.
This the Basis of mental Reproduction.—It is to this general principle of suggestion or association that we are indebted for all mental reproduction. It is only as one idea or feeling is suggested by some other which has gone before, and with which it is in some way, and for some reason, associated in our minds, that any former thought or sensationis recalled, that any object which we have perceived or any scene through which we have passed, is mentally reproduced. It is thus that the sight of an object brings to mind occurrences connected with it in our history, that the same recalls the thing, that the words of a language bring to mind the ideas which they denote, or the characters on the musical staff, the tones which they represent.
Not a distinct Faculty.—It has been customary to speak of association of ideas as a distinct faculty of the mind. It is not properly so ranked. It is a law of the mind rather than a faculty of it—a rule or method of its action in certain cases; and the particular power of mind to which this rule applies is that form of simple conception which we term mental reproduction.
The Term Suggestion preferred by Brown.—In place of the term association, Dr. Brown would prefer the term suggestion as more correct. To speak of the association of ideas implies that they have previously coëxisted in the mind, and that the one now recalls the other in consequence of that previous coëxistence. That this is often the case is doubtless true, but it is also true that in many cases one idea suggests another with which it has not previously been associated in our minds. It is not necessary to the suggestion that there should be any prior association. An object seenfor the first timesuggests many relative conceptions. The sight of a giant suggests the idea of a friend of diminutive stature, not because the two ideas have previously been associated, or the two objects have coëxisted, either in perception or conception, but because it is a law of the mind that one conception shall suggest another, either as similar, or as opposite, or in some other way related to it. This may be as truly a law of the mind, independent of association, as that light falling on the retina shall produce vision. It may seem mysterious that this should be so. Is it not equally mysterious that ideas which have formerly coëxisted should recall each other? The real mystery isthe recurrence in any mode, and from any source, of the idea, without the recurrence of the external producing cause. For these reasons, Dr. Brown prefers the termsuggestiontoassociation.
The Term Conception preferable to either.—As regards the activity ofthe mind itself, in the process of mental reproduction, the term conception seems to me to express more nearly the exact state of the case than either association or suggestion. An idea issuggested tothe mind by some external object; the mindconceivesthe idea thus suggested. The flute which I perceive lying on the table in the room of my friend suggests at once to my mind the idea of that friend. The action of the mind in this case is simply an act of conception. All that the flute does—all that we mean when we say the flute suggests the idea of the friend—is simply to place the mind in such a state that the conception follows. Whether we speak then of the laws ofassociation, laws ofsuggestion, or laws of mentalconception, is immaterial, provided we bear in mind the real nature of the process as now defined.
Question stated.—But what are the laws of association, or suggestion, so-called—in other words, of mental conception? Under what circumstances is a given conception awakened in the mind by some preceding conception or perception? This is an important subject of inquiry, and one which has not escaped the attention of philosophers.
Primary Laws.—It has been usual to enumerate as primary laws of suggestion, the following:resemblance,contrast,contiguity in time or place; to which has sometimes been addedcause and effect. There can be little doubt that these are important laws of suggestion; that given object of thought is likely to suggest to the mind that which is like itself, that which is unlike, that which is connected with itself in time and place, that of which it is the cause or the effect. Whether these principles are exhaustive, and whether they may not be reduced to some one general principle comprehensive of them all, may admit of question.
Law of Similars.—To begin withresemblance. It seems to be a law of our nature, that like shall remind us of like. The mountain, the forest, the river, that I see in my morning walk to-day, remind me of similar objects that were familiar to my childhood. Nor is it necessary that the resemblance should be complete. A single point of similarity is sufficient to awaken the conception of objects the most remote, and, in other respects, dissimilar. I pass in the street a person with blue eyes, or dark hair, or having some peculiarity of expression in the countenance, and am at once reminded of a very different person whom I knew years ago, or whom I met perhaps in another land; yet the two may be as unlike, except in the one point which attracts my attention, as any two persons in the world. An article of dress peculiar to the Elizabethan age, or to the court of Louis XIV. reminds us of the lordly dames and courtiers, or gallant warriors of those periods. A single feature in the landscape, perhaps a single tree, or projecting crag, on the mountain side, brings before us the picture of a scene widely different in most respects, but presenting only this one point of resemblance to the scene before us.
Not confined to Objects of Sight.—Nor is it the objects of sight alone that are suggestive of similar objects. The other senses follow the same law. Sounds suggest similar sounds; tastes, similar tastes; and along with the sounds, tastes, etc., thus recalled, are awakened conceptions of many things having no resemblance to the suggesting object, but associated in our previous perceptions with the object suggested. A certain succession of musical sounds, for example, recalls to the Swiss his native valley, and the mountains that shut it in, and brings back to his mind the scene of his childhood, and the peculiar customs of his father-land where he heard in former years that simple melody. With what a train of associations is a single name often fraught; what power of magic lies often in a single word!
Illustrations of other Laws.—Of the other principles ofsuggestion or association which have been named, it is not necessary to speak minutely. Their operation is obvious and indisputable. Illustrations will occur to every one. The palace of the king reminds us by contrast of the hovel of the peasant. The splendor of wealth and luxury suggests the wretchedness of poverty and want. The giant reminds us of the dwarf, and the dwarf of the giant. On the principle of contiguity in time and place, the sight of an object reminds us of events that have occurred in connection with it; the name Napoleon suggests Waterloo, and Wellington, and the marshals of the empire; St. Peter's and the Vatican suggest Raphael and his Transfiguration; a book, casually lying on my table, reminds me of the volume that formerly stood by its side on the shelf, and so carries me back to other scenes, and other days.
In like manner, if it be not indeed the operation of the same principle, cause suggests the effect, and effect its cause. The wound reminds me of the instrument, and the instrument awakens the unpleasant conception of the wound which it once inflicted.
Why one Conception rather than another.—Inasmuch as any one conception may awaken in the mind a great variety of other conceptions—since a picture, for example, may recall the person whose likeness it is, or the artist who painted it, or the friend who possesses it, or the time and place in which it was sketched, or the room in which it formerly hung, or any circumstance or event connected with it—the question arises, why, in any given instance, isoneof these conceptions awakened in the mind rather than anyotherin its stead? It is evident that the action of the associating principle is not uniform, sometimes one conception being awakened, sometimes another.
Secondary Laws.—In answer to this, Dr. Brown has shown that the action of these general and primary laws of suggestion, now named, is modified by a variety of circumstances, which may be calledsecondarylaws of suggestion,and which will account for the variety in question. These modifying circumstances are: 1. Continuance of attention. 2. Vividness of feeling. 3. Frequency of repetition. 4. Lapse of time. 5. Exclusiveness of association. 6. Original constitutional differences. 7. State of mind at the time. 8. State of body. 9. Professional habits. Any one of these circumstances may so modify the action of the primary laws of suggestion, that one conception shall be awakened in the mind rather than another, by that which has preceded.
Correctness of this View.—There can be little doubt as to the correctness of this view. The attention, for example, which a given object or event excites at the time of its occurrence, and the strength and liveliness of feeling which it awakened in us, have very much to do, as every one knows, with our subsequent remembrance of that object or event. So also has the frequency with which the train of thought has been repeated—a fact illustrated in the process of committing to memory.
The more frequently two things come together before the mind, the more likely will it be, when one is again presented, to think of the other. In the process of learning a thing by rote, we repeat the lines over and over, until they become so associated, and linked together, that the suggestion of one recalls the whole. Frequently, however, we find it difficult to pass from one sentence to another, or from one stanza or paragraph to another, while we find no difficulty in completing the sentence or paragraph once commenced. The reason is, we have repeated each sentence or stanza by itself in the process of learning, and have not connected one with another. The last words of one sentence, and the first words of another, have not been repeatedly conjoined in the mind—have not frequentlycoëxisted.
Sometimes, however, a more than usual vividness of conception will make up for the want of this frequent coëxistence. When, for any reason, as excited feeling, or extraordinary interest in what we perceive, we grasp withpeculiar clearness and force the idea presented, this vividness of mental conception will, of itself, insure the remembrance of the object contemplated. A man, on trial for his life, will be likely to recollect the faces and tones of each of the different witnesses on the stand, and the different judges and advocates, even if he never sees them afterward.
We all know, also, that the lapse of time weakens the impression of any object or event upon the mind, and so lessens the probability of its recurrence to the thoughts. We more readily recall places and objects seen in a recent tour, than those seen a year ago. The exclusiveness of the connection is also an important circumstance. An air of music, which I have heard played or sung only on one occasion, and by one musician only, is much more likely, when heard again, to bring to mind the former player, than if it had also been associated with other occasions and other performers. Much depends, moreover, on native differences of temperament, on the habitual joyousness, or habitual gloom, which may pervade the spirits, on the lights and shadows which passing events may cast, in quick succession, on the mind, as good or bad news, the arrival of a friend, the failure of an enterprise, a slight derangement of any of the bodily functions, or even the state of the atmosphere. All these circumstances have much to do with the question, whether one conception or another shall be awakened in the mind by any object presented to its thoughts.
These Laws distinguished as Objective and Subjective.—It will be observed that the primary laws of suggestion, so called, are such as arise from the relations which our thoughts sustain to each other, while the secondary are such as arise from the relations which they sustain to ourselves, the thinking subjects. Hence the former have been calledobjective, the latter,subjectivelaws.
Possibility of reducing the primary Laws to one comprehensive Principle.—I have already suggested that possibly the primary laws admit of being reduced to some onegeneral and comprehensive principle. This is a point deserving attention. Were we required to name some one principle which should comprehend these several specific laws of association, it would be that of the prior existence in the mind of the suggesting and the suggested idea. The two conceptions have, for some reason, and at some time, stood together before the mind, and hence the one recalls the other.It seems to be a general law of thought,that whatever has been perceived or conceived in connection with some other object of perception or thought, is afterward suggestive of that other.The relation may be that of part to whole, of resemblance, of contiguity, or contrast, or cause; it may be a natural or an artificial relation; whatever it is that serves as the connecting link between one thought and another, as they come before the mind at first, that will also serve as the ground of subsequent connection, when either of these thoughts shall present itself again to the mind. The one will suggest the other.
Application of this Principle to the several Laws of Suggestion.—Why is it, for example, that things contiguous in time and place suggest each other? In consequence of that contiguity they were viewed by the mind in connection with each other; as,e. g., the handle, and the door to which it belongs, the book, and its neighbor on the shelf. It is because Napoleon and his marshals, Wellington and Waterloo, have been presented together to the thoughts, that one now recalls the other. For the same reason the light hair and blue eyes of the person passing in the street recall the friend of former years; that peculiarity of hair and of eyes has been, in my mind, previously connected with the conception of my friend. So also a part suggests the whole with which it has been ordinarily connected, as, for example, the crystal and the watch.
Further Application of the same Principle.—On the same principle cause and effect are naturally suggestive. We have been accustomed to observe the elision of a sparkin connection with the forcible collision of flint and steel and whenever we have observed the application of fire to gunpowder, certain consequences have uniformly attracted our attention; hence the one of these things awakens immediately in our minds the conception of the other, with which it has previously coëxisted. For the same reason the instrument suggests the idea of the wound, and the wound of the instrument. The sight of a rose, and the sensation of fragrance, have usually coëxisted; hence either recalls the other.
The connection in this case is natural. Let us suppose a case in which it shall be arbitrary, or artificial. Suppose I happen to hold a rose in my hand, at the same moment a certain unusual noise is heard in the street, or at the moment when an eclipse of the sun becomes visible; on seeing the rose the next day I am instantly reminded of the noise, or of the eclipse, that was connected with it in my previous perception.
Application to the Law of Opposites.—On the same principle opposites also suggest each other. They sustain a certain relation to each other in our thoughts, and are in a sense necessary to each other in thought, as,e. g., white and black, crooked and straight, tall and short; which arerelativeideas, neither of which is complete by itself without the other; the one the complement of the other; each, so to speak, the extreme term of a comparison. As such they stand together before the mind, in its ordinary perceptions, and hence the one almost of necessity recalls the other.
The same Principle suggested by Dr. Brown.—The possibility of reducing the laws of association to one common principle, as now attempted, namely that of prior coëxistence in the mind, has not altogether escaped the notice of philosophers. Dr. Brown, in more than one passage, advances the idea, that on a sufficiently minute analysis "all suggestion may be found to depend on prior coëxistence, or, at least, on such immediate proximity, as is itself, veryprobably, a modification of coëxistence." In order to this nice reduction, however, he adds, we must take into account "the influence of emotions, and other feelings that are very different from ideas; as when an analogous object suggests an analogous object by the influence of an emotion or sentiment, which each separately may have produced before, and which is therefore common to both." As illustrative of this, he refers, among others, to cases of remote resemblance; as when, "for example, the whiteness of untrodden snow brings to our mind the innocence of an unpolluted heart; or a fine morning of spring, the cheerful freshness of youth." In such cases, he says, "though there may never have been in the mind any proximity of the very images compared, there may have been a proximity of each to an emotion of some sort, which, as common to both, might render each capable, indirectly, of suggesting the other." The same principle he applies to suggestion by contrast, as when the sight of a person with a remarkably long nose brings to mind some one whom we have seen with a nose as remarkable for brevity; the common feeling in the two cases being that of surprise or wonder at the peculiarity of this feature of the countenance.