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

by Thomas Brown

In this manner, I endeavoured to explain to you, how our knowledge of the mere length of bodies may have been acquired, from varieties of length that are recognized as coexisting and proximate, and are felt to unite, as it were, and terminate in our sensation of resistance, which interrupts them equally, and interrupts always a greater number of the coexisting truths, in proportion to the size of the body compressed; and, in a similar manner, our notions of the other dimensions of bodies, which are only these varieties of length in different directions. I cannot conclude this summary, however, without recalling to your attention, a very simple experiment, which I requested you to make for yourselves,—an experiment, that, even in the unfavourable circumstances in which it must now be tried, is yet, I conceive, demonstrative of the influence of mere time, as an element of that complex notion, which we have been examining, when the more rapid measurements of vision,—which are confessedly not original but acquired,—are excluded. If, in passing our finger, with different degrees of slowness or rapidity, along the same surface, with our eyes shut,—even though we should previously know the exact boundaries of the extent of surface,—we feel it almost impossible not to believe,—and but for the contrary evidence of vision, could not have hesitated a single moment in believing,—that this extent is greater or less, according as the time employed in performing exactly the same quantity of motion, with exactly the same force of pressure, on the same quantity of our organ of touch, may have been greater or less,—it must surely be admitted, that the notion of the length, which thus uniformly varies with the time, when all other circumstances are the same, is not absolutely independent of the time,—or it must, in like manner, be believed, that our notion of visual distance, which varies with the distribution of a few rays of light on the small expanse of the optic nerve, is yet independent of those faint shades of colouring, according to the mere varieties of which, it seems at one time to lay open to our view a landscape of many miles, and at another time to present to us, as it were before our very eyes, an object of scarcely an inch in diameter. The greater dimness, and diminished size of a few objects in the back ground of a picture, which is in itself one coloured plane of light, does not more truly seem to increase the line of distance of those objects, than, in the other case, the increased slowness of the motion of our hand along any surface, seems to lengthen the line which separates one of its boundaries from the other.

That we now seem to perceive extension, immediately by touch, cannot be denied; and, in a case so obscure as this,—with our very limited knowledge, and our very limited power of adding to this knowledge,—it may seem the most prudent, and perhaps even the most suitable,—as it is, without all question, by far the easiest part,—to acquiesce in the opinion, that the perception, which now seems immediate, was so originally,—that the belief of the presence of an external figured body, is, by the very constitution of our nature, attached to a certain affection of the mere organ of touch. But, since there are circumstances,—as we have seen,—which show this opinion, when very nicely examined, to be inadmissible, we may, at least, attempt to proceed a little farther, if we do this with a sufficient sense of the very great difficulty of the attempt, in relation to our power and knowledge, and consequently with a very humble assurance, as to the certainty of any opinion which we may be led to form. To know the mind well, is to know its weaknesses as well as its powers; and it is precisely in a case of this sort, that he, whose knowledge is least imperfect, will be the best judge of its imperfection, and, therefore, the least disposed to put complete reliance on it in his own speculations,—or to assert it dogmatically, when he offers it, as all opinions, on so very obscure a subject, should be offered, to the inquiry, rather than to the undoubting assent.

The analysis, I own, is one which must require a considerable effort of attention on your part, because it is truly one of the most subtile on which I could call you to enter. But you must be aware, that this subtlety is in the nature of the very inquiry itself; since it is an inquiry into the elements and progressive growth of feelings, which seem to us, at present, simple and immediate, and that the alternatives, therefore, are not those of greater or less subtlety and refinement of analysis, but of attempting the analysis, or abandoning it altogether.

Before proceeding farther, in our inquiry with respect to the origin of the notion of extension, it may, however, be of advantage, to take a short retrospect of the progress which we have already made; for, if we have found nothing more, we have, at least, as I conceive, found reason to reject a considerable part of our former belief on the subject, which, though a negative acquisition, is yet a very important one. Though we should not be able to discover the true source of the notion which we seek, it is something, at least, to know, that we have little reason to expect to find it, where we have uniformly been accustomed to seek it.

In the first place, then, we have seen the fallacy of the supposition, that our knowledge of extension may be easily accounted for, by the similarity in figure of the compressed part of the organ of touch to the compressing body, since the notion of extension is not a state of the material organ, compressed and figured, which, as mere matter, however exquisitely organized, is as little capable of this notion, as of smell, or taste, love or aversion, but, a state of the mind itself, which is susceptible of shape or pressure, being as little square, when it perceives a square, as when it perceives a circle; and any affection of which, therefore, may be supposed as much to follow any one shape, as any other shape of the mere external organ. If, indeed, as this explanation most strangely seems to assume, we could be supposed to have any previous knowledge of the shape of our organ of touch, nothing more would be necessary, for we should then have a perfect knowledge of extension, though no other extended body but our own organ of touch were in existence. To refer us to the organ is, however, only to bring the very same difficulty one step nearer, since previously to the application of an external body, the mind has as little knowledge of the shape of its organ of touch, as it has of the body compressing it; and it is manifestly most absurd, to ascribe the origin of our knowledge of extension, to our knowledge of the resemblance in figure of an external body to our organ; since this very knowledge of the resemblance must imply the previous knowledge of the figure of both, and consequently of that very extension, which, according to this supposition, must be known to us BEFORE it is known.

In the second place, we have seen, that, if the configuration of the sensorial organ were the only circumstance necessary, to induce, immediately, in mind, the notion of figure, this notion should accompany every sensation of every kind; the smell of a rose, for example, as much as the pressure of a cube or a sphere: for the nervous expansion, in the organ of smell, and in every other organ, is of a certain figure, before sensation, during sensation, and after sensation, as much as the nervous expansion of the organ of touch. And, though we were to confine ourselves wholly to this organ, the nervous matter in it is, at all times, of a certain shape, as much when there is no pressure on it, as when it is exposed to such pressure; yet the mere figure of the organ of touch, is not then accompanied with the mental notion of its figure; nor is this the case, merely when the sense is quiescent, but, in many cases, in which it is affected in the most lively manner; as, for example, when we are exposed to great cold or heat, in which cases, the shape of this very tactual organ, thus strongly affected, is as much unperceived by us, as when there is no affection of it whatever.

Lastly, which is a point of much more importance, because it has relation to the only philosophic view of touch, as the immediate organ of extension; the view, in which the mere configuration of the compressed organ, as similar to that of the compressing body, is laid out of account, and the immediate belief of extension is supposed to depend on the original constitution of the mind, by which its affections have been arranged, so as to correspond with certain affections of the bodily organs; the mental state which constitutes the perception of a square, arising immediately when the organ of touch is affected, in a certain manner, as that mental state which constitutes the sensation of the fragrance of a rose, arises immediately, when the organ of smell is affected, in a certain manner; this opinion too, philosophic as it is, compared with those which we before considered, though, in truth, it only assumes the point in question, without attempting to solve any difficulty, supposed to be connected with it, we have yet found to be as little tenable, as the opinions that suppose the mental notion of figure to depend on the peculiar figure of the compressed material organ. The consideration which, as I stated in my last Lecture, seems to me decisive on this point, is, that, if touch inform us of extension immediately, as smell informs us of fragrance, sight of colour, and hearing of sound; it must do this in every instance, without relation to particular figure, as smell, sight, and hearing, extend to all odours, hues, and sounds; for it would certainly be, as I said, a very strange abuse of the license of supposition, to imagine that we perceive a square immediately by touch, but not a circle; or a circle, but not a square; or any one figure, but not any other figure. In short, if figure be the direct primary object of touch, as sight is of vision, we should feel immediately every form impressed, as we see immediately every colour. It is only when the figures are very simple and regular, however, such as we might be supposed to have easily learned, in the same manner as we learn, visually, to judge of distances, that we are able to discover them, as it were, immediately, by touch; and, even when we are able, in this manner, to determine the species of figure, that is to say, the mere outline of a body, we are rarely able to determine the exact magnitude which that outline comprehends; yet, as our organ must be affected by each part of the compressing surface, by the central parts, as much as by the exterior parts which form its outline, and by these, as much as by the central parts; and as every feeling which the organ directly affords, must be immediate, when there is no change of the position, or other circumstances of the object, that might vary the sensation, we should, if mere touch communicated to us the knowledge supposed, be able to determine, exactly and instantly, the magnitude and figure; or, it is evident, that the determination of magnitude and figure must depend wholly, or in part, on something that is different from touch. The magnitude we are far from being able to discover exactly, even of simple figures; and when the form is very irregular, and we know nothing more, than that a certain body is pressed against our hand,—the magnitude and figure are alike difficult to be discovered; so difficult, that I may safely say, that no one, who makes the experiment, will find, on opening his eyes, that his tactual or intellectual measurement has, in any one case, been exact, or his notion of the figure half so distinct as it now is, after a single glance. Can we then think that it is by mere touch we discover figure, as exactly as by the glance of our mature vision,—that we discover it, in all its varieties, originally by touch, and as accurately at first, as after innumerable trials,—when we discover it, only in a few cases, that are previously familiar to us, and even in these very imperfectly? The determination of the form impressed, in which we are almost conscious of a sort of intellectual measurement, has surely a much greater resemblance to the perceptions, which we term acquired, than to those which are immediate. In vision, for example, when the original power of that sense has been strengthened and enriched, by the acquisitions which it is capable of receiving from other sources, we see a long line of distance before us; and the small distances with which we are familiar, we distinguish with sufficient accuracy; but, in our visual measurement of greater distances, we are almost certain to err, taking often the less for the greater, and the greater for the less. It is precisely the same in touch. When a small body, which we have never seen, is pressed upon our hand, we are able, if its surface be square, or circular, or of any other form, with which we are well acquainted, to determine its figure, without much hesitation; because we have learned, tactually, to distinguish these regular figures. But, in endeavouring to determine, in this manner, by touch alone, the figure of any irregular body, less familiar to us, though, as a direct object of sense, if touch be the sense of figure, it should be equally and as immediately tangible as the most regular form, we feel a hesitation of the same sort, as when we attempt to ascertain by our eye, the exact distance of a remote object. To know extension or figure, is to know, not one point merely in the surface of a body, but many continuous points; and if, when the surface, is circular, we know these continuous points, and their relation to each other, immediately on pressure, we must know, as immediately, the same points and their relations, though the surface comprehending them, instead of being circular, should be of an outline more irregular. We certainly cannot know this irregular surface to have any extension at all, unless we know some parts of it; and, when the pressure is uniform from every point, and the organ of touch uniform, on which the pressure is made, it would be absurd to suppose, that we know fifty, or eighty, of the hundred points which form the impressing surface, but cannot determine its figure, because we are ignorant of the twenty of fifty remaining points; when these remaining points are acting on our organ of touch, in exactly the same manner as the fifty or eighty which we know, and when, if the surface containing merely the same number of points, had been circular, or of any other single form, as familiar to us, the whole hundred points would have been known to us equally and at once.

When our perceptions of form, then, are so various and irregular, and are more or less quick and precise, exactly as the shape which we endeavour to determine, has more or less resemblance to shapes that are familiar to us, it does not seem too bold an inference to conclude, that the knowledge of figure, which, as all extension that is capable of being perceived by us, must have some boundary, is nothing more than the knowledge of extension, is not the state of mind originally and immediately subsequent to affections of our organs of touch, any more than the perception of distance is the state of mind originally and immediately subsequent to affections of our organ of sight; and the very striking analogy of these two cases, it will be of great importance for you to have constantly in view; as it will render it less difficult for you to admit many circumstances, with respect to touch, which you might otherwise have been slower to conceive. That we should seem to perceive extension immediately by touch, though touch originally, and of itself, could not have afforded this perception, will not then appear more wonderful, than the apparently immediate perception of distance by the eye, which, of itself, originally afforded us no perception of that sort; nor the impossibility of feeling a body, without the notion of it, as extended, be more wonderful than the similar impossibility of separating colour from extension, in the case of distant vision. Above all, the analogy is valuable, as shewing the closeness and indissolubleness of the union, which may be formed of feelings that have in themselves no resemblance. What common properties, could we have conceived in vision, and that absolute blindness, which has never had a single sensation from light! and, yet, it is worthy of remark, that the perceptions of the blind, in consequence of this singular power of association, form truly the most important part of those very perceptions of vision, of which, as a whole, they are unfortunately deprived. We do not merely see with our eyes, what we may have felt with our hands; but our eyes, in the act of vision, have borrowed, as it were, those very sensations.

The proof, that our perception of extension by touch, is not an original and immediate perception of that sense, is altogether independent of the success of any endeavour which may be made, to discover the elements of the compound perception. It would not be less true, that touch does not afford it, though we should be incapable of pointing out any other source, from which it can be supposed to be derived. Of the difficulty of the attempt, and the caution with which we should venture to form any conclusion on the subject, I have already spoken. But the analysis, difficult as it is, is too interesting not to be attempted, even at the risk, or perhaps I should rather say, with the very great probability, of failure.

In such an analysis, however, though we are to proceed with the greatest caution, it may be necessary to warn you, that it is a part of this very caution, not to be easily terrified, by the appearance of paradox, which the result of our analysis may present. This appearance we may be certain, that any analysis which is at all accurate must present, because the very object of the analysis is to shew, that sensations, which appear simple and direct, are not simple,—that our senses, in short, are not fitted, of themselves, to convey that information, which they now appear, and through the whole course of our memory have appeared to us instantly to convey. It is very far, indeed from following, as a necessary consequence, that every analysis of our sensations which affords a paradoxical result, is, therefore, a just one—for error may be extravagant in appearance as well as in reality. But it may truly be regarded as a necessary consequence, that every accurate and original analysis of our sensations must afford a result, that, as first stated, will appear paradoxical.