Lectures on the Philosophy of the Human Mind (Vol. 1 of 3)

by Thomas Brown

Of these, I may mention, in the first place, the sensations of heat and cold,—sensations that arise from affections of our nerves of touch, or at least from affections of nerves, which, as equally diffused and intermingled with them, it is impossible to distinguish from those which constitute our organ of touch, the same wide surface rendering us sensible, as it were, at every point of warmth as of pressure.

I have also remarked to you, how little analogy there is of our sensations of warmth, to the other sensations commonly ascribed to this organ; and the great difference of the feelings, has led some physiologists to believe, that the organs of sensations so different, must themselves be different. But even though the sensations were as dissimilar as is supposed, there is no reason a priori to believe,—and to experience, it is evident, that, in this case, we cannot appeal, so as to derive from it any ground for believing,—that sensations, which are very different, must arise from affections of different organs. As far, indeed, as we can safely appeal to experience, in this very case, there are sensations which we never hesitate in referring to our tactual nerves, as different from the more common sensations ascribed to touch, as the sensation of warmth itself. I allude to the pain of puncture or laceration of the skin. Indeed, if the brain be ultimately the great organ of all our sensations, it is evident that we must refer to affections of one sensorial organ, not the various feelings of touch only, but, with them the still greater variety of feelings, that constitute our sensations of smell, taste, sound, and colour.

But are we indeed sure, that there truly is that great dissimilarity supposed, or may not our belief of it arise from our reference to touch of sensations that truly do not belong to it? Such, at least, is the opinion, to which, I think, a nicer analysis will lead us. The primary original feelings, which we owe to our mere organ of touch, I consider as of a kind, all of which are far more analogous to the sensations of warmth, or of pain on puncture, than to the perceptions of form and hardness, which are generally regarded as tangible. Before entering on the analysis, however, it will be necessary to consider, what are the sensations which we are supposed to owe to this organ.

The sensations of heat and cold,—as received from our organ of touch,—we may almost lay out of account in our analytical inquiry. It is unnecessary to dwell on them, or even to repeat, in application to them, the argument, which has been already applied more than once to the sensations before considered. It is quite evident, that, in classing our warmth or chillness, as a sensation,—and not as a feeling that has arisen spontaneously in the mind,—we are influenced by that experience, which has previously given us the belief of objects external,—at least, of our own corporeal frame,—and that, if we had been unsusceptible of any other sensations, than those of heat and cold, we should as little have believed these to arise directly from a corporeal cause, as any of our feelings of joy or sorrow. The same remark may be applied to the painful sensations of puncture and laceration.

It is only to the other more important information ascribed to the sense of touch, therefore, that our attention is to be directed.

By touch, we are commonly said to be made acquainted with extension, magnitude, divisibility, figure, motion, solidity, liquidity, viscidity, hardness, softness, roughness, smoothness. These terms, I readily allow, are very convenient for expressing notions of certain forms or states of bodies, that are easily distinguishable. But, though specifically distinguishable, they admit generically of very considerable reduction and simplification. Hardness and softness, for example, are expressive only of greater or less resistance,—roughness is irregularity of resistance, when there are intervals between the points that resist, or when some of these points project beyond others,—smoothness is complete uniformity of resistance,—liquidity, viscidity, are expressive of certain degrees of yieldingness to our effort, which solidity excludes, unless when the effort employed is violent. All, in short, I repeat, are only different species or degrees of that which we term resistance, whatever it may be, which impedes our continued effort, and impedes it variously as the substances without are themselves various. Such is one order, then, of the feelings commonly ascribed to the sense which we are at present considering.

To proceed to the other supposed tangible qualities, before included in our enumeration,—figure is the boundary of extension, as magnitude is that which it comprehends; and divisibility, if we consider the apparent continuity of the parts which we divide, is only extension under another name. If we except motion, therefore, which is not permanent, but accidental,—and the knowledge of which is evidently secondary to the knowledge which we acquire of our organs of sense, before which the objects are said to move, and secondary in a much more important sense, as resulting not from any direct immediate organic state of one particular moment, but from a comparison of sensations past and present,—all the information, which we are supposed to receive primarily and directly from touch, relates to modifications of resistance and extension.

Though it is to the sense of touch, however, that the origin of the knowledge of these is generally ascribed, I am inclined to think, in opposition to this opinion, that in both cases, the reference is wrongly made,—that if we had the sense of touch only, we should not be sensible of resistance, nor, I conceive, even of extension,—and that we seem to perceive the varieties of extension and resistance immediately by touch only, because the simple original tactual feeling has become representative of these, in the same manner, and for the same reason, as we seem to perceive the varieties of distance immediately by the eye. The sense of touch has unquestionably, like all our other senses, its own peculiar feelings, though, for the simple original feelings, attached to the affections of this most extensive of organs, we have unfortunately no name, but that which is applied in popular, and even in philosophic language, to all the affections of the mind. Our joy or grief, hope or fear, love or hate, I before remarked, we term feelings, as readily and frequently, as we use this term to express our sensations of touch; and that, which, however restricted in its original meaning, is now the common name of our mental affections of every class, has, by this extension, unfortunately, become a very unfit one, for distinguishing a limited order of those affections.

Whatever be the term, which we may use, however, there is, and must be, a sensation peculiar to touch, without regard to the extent or quantity of the surface impressed,—as there is, in colour, a sensation peculiar to vision, without regard to the extent of the portion of the retina on which the light may have fallen. Every physical point of our organ of touch, when existing in a certain state, is capable of inducing in the mind a peculiar feeling, though no other physical point of the organ were affected,—as every physical point of the retina, though but a single ray of light were admitted to the eye, is capable of inducing in the mind a peculiar affection of vision; and when many such physical points are affected together, by some impressing surface, the form of which we think that we discover immediately by touch, it is from experience only that we can learn the vicinity of the physical points of our own tactual surface thus impressed, and consequently the continued extension of the object which impresses them. Before we have so much knowledge of external things, as to know even that we have any bodily organs whatever,—and it is of this state of absolute ignorance alone that we must think, as often as we speculate on the information which our senses separately afford,—when we know as little of our bodily frame, as of that material universe, of which we know nothing, we cannot, by the very terms of this supposition, know that different points of our organ of touch are affected in a certain manner,—that these points are contiguous to each other—and that the mass affecting these contiguous points must consequently itself be composed of points, that are, in like manner, contiguous. We know nothing of our organs—we know nothing of any external masses—but a certain feeling is excited in our mind; and it is this simple feeling alone, whatever it may be, which constitutes the direct elementary sensation of touch, though this simple elementary sensation, like many other sensations, may afterwards be so blended with other feelings, as to become significant of them, and even to seem to involve them, as if originally and necessarily coexisting.

It is impossible for us at present, indeed, to have a body impressed on us, without the immediate notion of something external and extended,—as it is impossible for one, whose sight is perfect, to open his eyes, in the light of day, without perceiving, as it were immediately, the long line of variegated landscape, in the scenery before him:—the one impossibility is exactly equal to the other; yet we know, in the case of vision, that all which we immediately perceive, at the very moment, when our eyes seem to comprehend the worlds of half infinity, in the hemisphere on Which we gaze, is a small expanse of light,—if even, which I greatly doubt, there truly be, in our original perceptions of this sense, so much of extension, as is implied in the smallest possible expanse. In touch, in like manner, I conceive, that the immediate sensation, though, like colour, it may now seem inseparable from extension and outness,—if, on the authority of Berkeley, I may venture to use that barbarous but expressive term,—was, like colour, originally distinct from them,—that, by the mere original sensations of this organ, in short, we could as little know the existence of an impressing body, as, by the mere original sensations of vision, we could learn that such a body existed at the extremity of the room in which we sit.