Description

A child has, as far as we know, all the perceptive powers of a man. He questioned him a little as to how he knows what he does; in many cases, he will tell you that he never learned his mother tongue; he always knew it, or he knew it as soon as he came to have sense; it appears, then, that he does not possess the faculty of distinguishing, by simple contemplation, between an intuition and a cognition determined by others.

There can be no doubt that before the publication of Berkeley's book on Vision, it had been generally believed that the third dimension of space was immediately intuited, although, at present, nearly all admit that it was known by inference. We had been contemplating the object since this very creation of man, but this discovery was not made until we began to reason about it.

Does the reader know of the blind spot on the retina? take a number of this journal, turn over the cover so as to expose the white paper, lay it sideways upon the table before which you must sit, and put two cents upon it, one near the left hand edge, and the other to the right. Put your left hand over your left eye, and with the right eye look steadily at the left hand cent. then, with your right hand, move the right hand scent which is now plainly seen, towards the left hand. When it comes to a place near the middle of the page it will disappear—you cannot see it without turning your eye. Bring it to near to the other cent, or carry it further away, and it will reappear; but at that particular spot it cannot be seen. Thus it appears that there is a blind spot nearly in the middle of the retina; and this is confirmed by anatomy. It follows that the space we immediately see when one eye is closed is not, as we had imagined, a continuous oval, but is a ring, the filling up of which must be the work of the intellect. What more striking example could be desired of the impossibility of distinguishing intellectual results from intuitional data, by mere contemplation?

A man can distinguish different textures of cloth by feeling; But not immediately, for he requires to move his fingers over the cloth, which shows that he is obliged to compare the sensations of one instant with those of another...