odour, and as though sight, hearing, and smell, are one and the same sense. But now, as the motions emanating from external objects are distinguishable by the medium through which they are conveyed, the sentient organs alluded to must manifestly be different also. With respect to the Touch, however, this is still obscure, for it is impossible that a living body should be constituted out of air or water, as it must have some solidity; and there remains only this conclusion, that it must be a mixture of earth, and such other particles as have affinity with flesh, and the analogue of flesh. Thus, the body has, of necessity, been adapted for being the medium for the tangible sense, through which the several tangible impressions are to be conveyed; and that the impressions are manifold is shewn in the tongue being perceptive of tangible as well as sapid qualities. We are sensible, in fact, by this organ of all tangible as well as sapid qualities; and were the rest of the flesh, like the tongue, sensible of savour, then "Taste" and "Touch" would seem to be one and the same sense; but now we perceive, since they are not convertible, that they must be distinct senses.
It may be a question whether, as all bodies have depth, that is the third magnitude, any two bodies, which have between them another body, can be in contact; for neither the humid nor the liquid is incorporeal, as each must, of necessity, be water or hold
