distance of objects. That knowledge must be directly given in the very function and exercise of vision, as every one will admit, without going to the expense of an octavo volume to have it proved.
But we hold that no truth in mental philosophy is more incontestable than this, that the sight originally, and of itself, furnishes us with no knowledge of the eye, as we now know that organ to exist. It does not inform us that we have an eye at all. And here we may hazard an observation, which, simple as it is, appears to us to be new, and not unimportant in aiding us to unravel the mysteries of sensation; which observation is, that, in no case whatever, does any sense inform us of the existence of its appropriate organ, or of the relation which subsists between that organ and its objects, but that the interposition of some other sense[1] is invariably required to give us this information. This truth, which we believe holds good with regard to all the senses, is most strikingly exemplified in the case of vision, as we shall now endeavour to illustrate.
Let us begin by supposing that man is a mere "power of seeing." Under this supposition, we must
- ↑ It would not be difficult to show, that as, on the one hand, distance is not involved in the original intuitions of sight, so, on the other hand, proximity is not involved in the original intuitions of touch; but that, while it is the touch which establishes an interval between the organ and the objects of sight, it is the sight which establishes no interval between the organ and the objects of touch. Sight thus pays back every fraction of the debt it has incurred to its brother sense. This is an interesting subject, but we can only glance at it here.
