_Thirdly_, If we consider our body somewhat more distinctly, as made up of organs and instruments of perception and of motion, it will bring us to the same conclusion. Thus the common optical experiments show, and even the observation how sight is assisted by glasses shows, that we see with our eyes in the same sense as we see with glasses. Nor is there any reason to believe, that we see with them in any other sense; any other, I mean, which would lead us to think the eye itself a percipient. The like is to be said of hearing; and our feeling distant solid matter by means of something in our hand, seems an instance of the like kind, as to the subject we are considering. All these are instances of foreign matter, or such as is no part of our body, being instrumental in preparing objects for, and conveying them to, the perceiving power, in a manner similar to the manner in which our organs of sense prepare and convey them. Both are in a like way instruments of our receiving such ideas from external objects, as the Author of nature appointed those external objects to be the occasions of exciting in us. Glasses are evident instances of this; namely of matter which is no part of our body, preparing objects for and conveying them towards the perceiving power, in like manner as our bodily organs do. And if we see with our eyes only in the same manner as we do with glasses, the like may justly be concluded, from analogy, of all our other senses. It is not intended, by any thing here said, to affirm, that the whole apparatus of vision, or of perception by any other sense, can be traced through all its steps, quite up to the _living power_ of seeing, or perceiving: but that so far as it can be traced by experimental observations, so far it appears, that our organs of sense prepare and convey objects, in order to their being perceived, in like manner as foreign matter does, without affording any shadow of appearance, that they themselves perceive. And that we have no reason to think our organs of sense percipients, is confirmed by instances of persons losing some of them, the living beings themselves, their former occupiers, remaining unimpaired. It is confirmed also by the experience of dreams; by which we find we are at present possessed of a latent, and what would be otherwise an unimagined unknown power of perceiving sensible objects, in as strong and lively a manner without our external organs of sense, as with them.