r how it is that we perceive distance and things placed at a
distance by sight. For, that we should in truth see EXTERNAL space, and
bodies actually existing in it, some nearer, others farther off, seems to
carry with it some opposition to what has been said of their existing
nowhere without the mind. The consideration of this difficulty it was
that gave birth to my "Essay towards a New Theory of Vision," which was
published not long since, wherein it is shown (1) that DISTANCE or outness
is NEITHER IMMEDIATELY of itself PERCEIVED by sight, nor yet apprehended
or judged of by lines and angles, or anything that has a necessary
connexion with it; but (2) that it is ONLY SUGGESTED to our thoughts by
certain visible ideas and sensations attending vision, which in their own
nature have no manner of similitude or relation either with distance or
things placed at a distance; but, by a connexion taught us BY EXPERIENCE,
they come to signify and suggest them to us, after the same manner that
WORDS of any language suggest the ideas they are made to stand for;
insomuch that a man BORN blind and afterwards made to see, would not, at
first sight, think the things he saw to be without his mind, or at any
distance from him. See sect. 41 of the fore-mentioned treatise.

44. The ideas of sight and touch make two species entirely distinct and
heterogeneous. THE FORMER ARE MARKS AND PROGNOSTICS OF THE LATTER. That
the proper objects of sight neither exist without mind, nor are the
images of external things, was shown even in that treatise. Though
throughout the same the contrary be supposed true of tangible
objects--not that to suppose that vulgar error was necessary for
establishing the notion therein laid down, but because it was beside my
purpose to examine and refute it in a discourse concerning VISION. So
that in strict truth the ideas of sight, when we apprehend by them
distance and things placed at a distance, do not suggest or mark out to
us things ACTUALLY existing at a distance, but only admonish us what
ideas of touch will be imprinted in our minds at such and such distances
of time, and in consequence of such or such actions. It is, I say,
evident from what has been said in the foregoing parts of this Treatise,
and in sect. 147 and elsewhere of the Essay concerning Vision, that
visible ideas are the Language whereby the governing Spirit on whom we
depend informs us what tangible ideas he is about to imprint upon us, in
case we