to the organ on hint of this sort of touch, rather than on that of any other touch, and in any other organ? Is not the whole fancy of the mind seeing its eye because it is lit-is not the whole metaphor of light but a will-of-the-wisp to the self-complacent Hamilton?

same.

So far, then, as the sensation proper is the condition of the perception proper, we cannot say that Hamilton has, in any way, assisted us beyond the fact: we see neither the necessity nor the modus operandi of the Hamilton, indeed, says as much as this himself, for the sensation is to him nexus and it is not nexus, it is necessary and it is not necessary, and evidently at last he has simply blindly settled himself into the analogy of light. Why any such stimulus is,-how it acts,-what it does,-Hamilton, taking up his position in the nervous system, is even worse off for an answer here than common sense, which, unlike its professing votary, has really its seat on the ground. It is easy, in the straits of such questions, to bawl out TI, and threaten us with a charge of imbecility at the hands of Aristotle; but, in the end, is there a single difficulty removed? Can it, indeed, be said that any one single difficulty-whether physiological or psychological—as regards brain, and nerves, and light, and images, and vibrations, and tympana, and labyrinths, and what not, has received solution at the hands of Hamilton? The position in the nervous system is, in effect, not only gratuitous but idle; and it is very characteristic of Hamilton that he should return in his metaphysical lectures to his dogged or, and wind up, though weakly enough, with such passages as:

RESISTANCE SUBJECTIVE ALSO.

'99

'But whether the senses be instruments, whether they be media, or whether they be only particular outlets to the mind incarcerated in the body,-on all this we can only theorise and conjecture.'

Nor is Hamilton one whit luckier in the step to his second net than in that to his first. This step is resistance-voluntary locomotion resisted; and from what we know now, it will not be difficult to perceive that the transition thence to a world without is сараble of being met by the same principles which interposed beween the sensation proper and the perception proper. Resistance, that is, is but a subjective feeling, and how there should be any hint in it of an external object, constitutes the difficulty. Any mental experience, indeed, feeling or other, cannot be referred out, till there be an out known. Nor is it different with locomotion: this, too, would be simply a feeling, more or less intense, and would give no knowledge of movement till ideas of space and an external universe had been already formed; but for the formation of these ideas we find no competent provision supplied by Hamilton.

Hamilton, indeed, asserts direct perception of extension, and extension implies space; but as we have seen, he brings forward for himself no more than assertion; and we are compelled to indicate and demand the missing element of proof. The void between subjective sensation and objective perception he leaves unmediated; and we refuse to participate in the satisfaction he demands for his own mere spring. There are certainly times, however, when the simple

recoil from intension to extension seems insufficient to Hamilton himself-times when, as it appears, he would really mediate between the intensive sensation of the membrane on the one side, and its extensive perception on the other. We have such deliverances as these, for example:-'Sensations out of each other, contrasted, limited, and variously arranged;' 'sensations recognised as plural, and reciprocally external;' 'sensations relatively localised;' 'all sensations, whatsoever, of which we are conscious, as one out of another, eo ipso, afford us the condition of immediately and necessarily apprehending extension.' Now, to judge from such expressions as these, there is more in the thought of Hamilton than that it is simply fact, that the sensation is the condition of the perception: he evidently contemplates something of reason as well. In other words, it is in the peculiar reciprocity of the sensations that he sees the prototype of extension. With this, too, his physiological ideas cohere: he would regard the ultimate fibrils as the ultimate units of sensation;' and he unequivocally attributes to 'the smaller size of the papillæ and fibrils of the optic nerve the greater power we possess, in the eye, of discriminating one sensation as out of another, and, consequently, of apprehending extension.' The theory that seems involved or desiderated, however, admits of a very simple refutation. The phrase, 'sensations one out of another,' can mean only one or other of two things: either sensations one out of another as different from one another; or sensations that, as such, have parts-that are, in their own nature, plural,

DIFFERENT SENSATION NOT DIFFERENT PLACE. 101

out of one another, extended. Now, to take the latter alternative first, we have simply to point out that, in the matter of sensations, there are none such. Sensations are but subjective feelings; they possess intension not extension; and Hamilton has no authority to extend them to the latter. Physiologically there may be a certain breadth of surface affected, or, as in the eye, illuminated, and each nervous filament may correspond to a distinct unit of the sensation (light); but, psychologically, that is not so;-psychologically, it is the sensation (light) we know, and not the membrane; and this sensation (light), this subjective feeling, has degree, but not breadth.

Again, sensations out of one another, as different from one another, will give information of difference, but not of distance or separation-of different quality, but not of different place. If in different sensations, we find, not only difference of quality, but difference of place, then, evidently, this latter is something other than themselves-something that has been added to them. This, in fact, is one of Kant's strongest arguments for the original implication and primitive presupposition of space as an independent, à priori, or pure perception.

Without space, then, there is no possibility of a cognition on our part, whether of the first net on experience of a secondary quality, or of the second net (the outer world) on experience of what Hamilton calls a secundo-primary quality-resistance. Space is the indispensable, radical condition; and it is quite incapable of being deduced from any relation-re

ciprocal or other-of sensations. Nay, as we have seen already, the very attempt to derive a knowledge of space and the primary qualities-empirically—is, from the first, suicidal and absurd; and Hamilton's own sense of failure cannot help breaking out ever and anon in his own words. Even in the midst of reasonings about sensations reciprocally out of each other, he admits that space must be presupposed, else they would be reciprocally out of each other, only as different, but not as in different places; and, feeling, perhaps, the whole floor of natural realism thus sinking beneath him, he fairly gives way at last to a burst of ill-humour, as he exclaims:-' It is truly an idle problem to attempt imagining the steps by which we may be supposed to have acquired the notion of extension; when, in fact, we are unable to imagine to ourselves the possibility of that notion not being always in our possession!' It is quite characteristic, too, that, having thus given vent to his temper, and quite unconscious that he has at once supported, and demonstrated ignorance of, the relative doctrine of Kant, he can, in his stubborn mood, wind up:—'We have, therefore, a twofold cognition of space; a, an à priori, native imagination [not perception] of it in general, as a necessary condition of the possibility of thought [not experience]; and b, under that, an à posteriori or adventitious percept of it, &c.' [and thus he betrays unconsciousness that, to Kant, a and b are one and the same!]

In this way, then, it is patent that a physiological theory of the origin of our cognition of extension,