We have now probably said enough to convince the attentive reader, that the sense of sight, when brought under its own notice as a sensation, either directly, or through the ministry of the touch or of the imagination, (as it is when revealed to us in its organ,) falls very far—falls almost infinitely within its own sphere. Sight, revealing itself as a sense, spreads over a span commensurate with the diameter of the whole visible space; sight, revealing itself as a Sensation, dwindles to a speck of almost unappreciable insignificance, when compared with the other phenomena which fall within the visual ken. This speck is the organ, and the organ is the sentient circumference drawn inwards, far within itself, according to a law which (however unconscious we may be of its operation) presides over every act and exercise of vision—a law which, while it contracts the sentient sphere, throws, at the same time, into necessary objectivity every phenomenon that falls external to the diminished circle. This is the law in virtue of which subjective visual sensations are real visible objects. The moment the sight becomes one of its own sensations, it is restricted, in a peculiar manner, to that particular sensation. It now falls, as we have said, within its own sphere. Now, nothing more was wanting to make the other visual sensations real independent existences; for, quà sensations, they are all originally independent of each other, and the sense itself being now a sensation, they must now also be independent of it.
We now pass on to the consideration of the sense of touch.
Here precisely the same process is gone through which was observed to take place in the case of vision. The same law manifests itself here, and the same inevitable consequence follows, namely—that sensations are things—that subjective affections are objective realities. The sensation of hardness (softness, be it observed, is only an inferior degree of hardness, and therefore the latter word is the proper generic term to be employed)—the sensation of hardness forms the contents of this sense. Hardness, we will say, is originally a purely subjective affection. The question, then, is, how can this affection, without being thrust forth into a fictitious, transcendent, and incomprehensible universe, assume, nevertheless, a distinct objective reality, and be (not as it were, but in language of the most unequivocating truth) a permanent existence altogether independent of the sense? We answer, that this can take place only provided the sense of touch can be brought under our notice as itself hard. If this can be shown to take place, then as all sensations which are presented to us in space necessarily exclude one another, are reciprocally out of each other, all other instances of hardness must of necessity fall as extrinsic to that particular hardness which the sense reveals to us as its own; and, consequently, all these other instances of hardness will start into being, as things endowed with a permanent and independent substance.
Now, what is the verdict of experience on the subject? The direct and unequivocal verdict of experience is, that the touch reveals itself to us as one of its own sensations. In the finger-points more particularly, and generally all over the surface of the body, the touch manifests itself not only as that which apprehends hardness, but as that which is itself hard. The sense of touch vested in one of its own sensations (our tangible bodies namely) is the sense of touch brought within its own sphere. It comes before itself as one sensation of hardness. Consequently all its other sensations of hardness are necessarily excluded from this particular hardness; and, falling beyond it, they are by the same consequence built up into a world of objective reality, of permanent substance, altogether independent of the sense, self-betrayed as a sensation of hardness.
But here it may be asked, If the senses are thus reduced to the rank of sensations, if they come under our observation as themselves sensations, must we not regard them but as parts of the subjective sphere; and though the other portions of the sphere may be extrinsic to these sensations, still must not the contents of the sphere, taken as a whole, be considered as entirely subjective, i.e. as merely ours, and consequently must not real objective existence be still as far beyond our grasp as ever? We answer. No, by no means. Such a query implies a total oversight of all that experience proves to be the fact with regard to this matter. It implies that the senses have not been reduced to the rank of sensations—that they have not been brought under our cognizance as themselves sensations, and that they have yet to be brought there. It implies that vision has not been revealed to us as a sensation of colour in the phenomenon the eye—and that touch has not been revealed to us as a sensation of hardness in the phenomenon the finger. It implies, in short, that it is not the sense itself which has been revealed to us, in the one case as coloured, and in the other case as hard, but that it is something else which has been thus revealed to us. But it may still be asked, How do we know that we are not deceiving ourselves? How can it be proved that it is the senses, and not something else, which have come before us under the guise of certain sensations? That these sensations are the senses themselves, and nothing but the senses, may be proved in the following manner.
We bring the matter to the test of actual experiment. We make certain experiments, seriatim, upon each of the items that lie within the sentient sphere, and we note the effect which each experiment has upon that portion of the contents which is not meddled with. In the exercise of vision, for example, we remove a book, and no change is produced in our perception of a house; a cloud disappears, yet our apprehension of the sea and the mountains, and all other visible things, is the same as ever. We continue our experiments, until our test happens to be applied to one particular phenomenon, which lies, if not directly, yet virtually, within the sphere of vision. We remove or veil this small visual phenomenon, and a totally different effect is produced from those that took place when any of the other visual phenomena were removed or veiled. The whole landscape is obliterated. We restore this phenomenon—the whole landscape reappears: we adjust this phenomenon differently—the whole landscape becomes differently adjusted. From these experiments we find, that this phenomenon is by no means an ordinary sensation, but that it differs from all other sensations in this, that it is the sense itself appearing in the form of a sensation. These experiments prove that it is the sense itself, and nothing else, which reveals itself to us in the particular phenomenon the eye. If experience informed us that the particular adjustment of some other visual phenomenon (a book, for instance) were essential to our apprehension of all the other phenomena, we should, in the same way, be compelled to regard this book as our sense of sight manifested in one of its own sensations. The book would be to us what the eye now is: it would be our bodily organ: and no à priori reason can be shown why this might not have been the case. All that we can say is, that such is not the finding of experience. Experience points out the eye, and the eye alone, as the visual sensation essential to our apprehension of all our other sensations of vision, and we come at last to regard this sensation as the sense itself. Inveterate association leads us to regard the eye, not merely as the organ, but actually as the sense of vision. We find from experience how much depends upon its possession, and we lay claim to it as a part of ourselves, with an emphasis that will not be gainsaid.
An interesting enough subject of speculation would be, an enquiry into the gradual steps by which each man is led to appropriate his own body. No man's body is given him absolutely, indefeasibly, and at once, ex dono Dei. It is no unearned hereditary patrimony. It is held by no à priori title on the part of the possessor. The credentials by which its tenure is secured to him, are purely of an à posteriori character; and a certain course of experience must be gone through before the body can become his. The man acquires it, as he does originally all other property, in a certain formal and legalized manner. Originally, and in the strict legal as well as metaphysical idea of them, all bodies, living as well as dead, human no less than brute, are mere waifs—the property of the first finder. But the law, founding on sound metaphysical principles, very properly makes a distinction here between two kinds of finding. To entitle a person to claim a human body as his own, it is not enough that he should find it in the same way in which he finds his other sensations, namely, as impressions which interfere not with the manifestations of each other. This is not enough, even though, in the case supposed, the person should be the first finder. A subsequent finder would have the preference, if able to show that the particular sensations manifested as this human body were essential to his apprehension of all his other sensations whatsoever. It is this latter species of finding—the finding, namely, of certain sensations as the essential condition on which the apprehension of all other sensations depends; it is this finding alone which gives each man a paramount and indisputable title to that "treasure trove" which he calls his own body. Now, it is only after going through a considerable course of experience and experiment, that we can ascertain what the particular sensations are upon which all our other sensations are dependent. And therefore were we not right in saying, that a man's body is not given to him directly and at once, but that he takes a certain time, and must go through a certain process, to acquire it?
The conclusion which we would deduce from the whole of the foregoing remarks is, that the great law of living[21] sensation, the rationale of sensation as a living process, is this, that the senses are not merely presentative—i.e. they not only bring sensations before us, but that they are self-presentative—i.e. they, moreover, bring themselves before us as sensations. But for this law we should never get beyond our mere subjective modifications; but in virtue of it we necessarily get beyond them; for the results of the law are, 1st, that we, the subject, restrict ourselves to, or identify ourselves with, the senses, not as displayed in their primary sphere, (the large circle A,) but as falling within their own ken as sensations, in their secondary sphere, (the small circle A.) This smaller sphere is our own bodily frame; and does not each individual look upon himself as vested in his own bodily frame? And 2ndly, it is a necessary consequence of this investment or restriction, that every sensation which lies beyond the sphere of the senses, viewed as sensations, (i.e. which lies beyond the body,) must be, in the most unequivocal sense of the words, a real independent object. If the reader wants a name to characterise this system, he may call it the system of Absolute or Thorough-going presentationism.