Phil. Sight therefore doth not suggest, or any way inform you, that the visible object you immediately perceive [pg 413] exists at a distance[812], or will be perceived when you advance farther onward; there being a continued series of visible objects succeeding each other during the whole time of your approach.
Hyl. It doth not; but still I know, upon seeing an object, what object I shall perceive after having passed over a certain distance: no matter whether it be exactly the same or no: there is still something of distance suggested in the case.
Phil. Good Hylas, do but reflect a little on the point, and then tell me whether there be any more in it than this: From the ideas you actually perceive by sight, you have by experience learned to collect what other ideas you will (according to the standing order of nature) be affected with, after such a certain succession of time and motion.
Hyl. Upon the whole, I take it to be nothing else.
Phil. Now, is it not plain that if we suppose a man born blind was on a sudden made to see, he could at first have no experience of what may be suggested by sight?
Hyl. It is.
Phil. He would not then, according to you, have any notion of distance annexed to the things he saw; but would take them for a new set of sensations, existing only in his mind?
Hyl. It is undeniable.
Phil. But, to make it still more plain: is not distance a line turned endwise to the eye[813]?
Hyl. It is.