hear distance in like manner as I say
that I see it, the ideas perceived by hearing not being so apt to be
confounded with the ideas of touch as those of sight are. So likewise a
man is easily convinced that bodies and external things are not properly
the object of hearing; but only sounds, by the mediation whereof the idea
of this or that body or distance is suggested to his thoughts. But then
one is with more difficulty brought to discern the difference there is
betwixt the ideas of sight and touch: though it be certain a man no more
sees and feels the same thing than he hears and feels the same thing.

48. One reason of which seems to be this. It is thought a great absurdity
to imagine that one and the same thing should have any more than one
extension, and one figure. But the extension and figure of a body, being
let into the mind two ways, and that indifferently either by sight or
touch, it seems to follow that we see the same extension and the same
figure which we feel.

49. But if we take a close and accurate view of things, it must be
acknowledged that we never see and feel one and the same object. That
which is seen is one thing, and that which is felt is another. If the
visible figure and extension be not the same with the tangible figure and
extension, we are not to infer that one and the same thing has divers
extensions. The true consequence is that the objects of sight and touch
are two distinct things. It may perhaps require some thought rightly to
conceive this distinction. And the difficulty seems not a little
increased, because the combination of visible ideas hath constantly the
same name as the combination of tangible ideas wherewith it is connected:
which doth of necessity arise from the use and end of language.

50. In order therefore to treat accurately and unconfusedly of vision, we
must bear in mind that there are two sorts of objects apprehended by the
eye, the one primarily and immediately, the other secondarily and by
intervention of the former. Those of the first sort neither are, nor
appear to be, without the mind, or at any distance off; they may indeed
grow greater or smaller, more confused, or more clear, or more faint, but
they do not, cannot approach or recede from us. Whenever we say an object
is at a distance, whenever we say it draws near, or goes farther off, we
must always mean it of the latter sort, which properly belong to the
touch, and are not so truly perceived as suggested