this difficulty: and I believe it not impossible to find one, provided we
examine it to the bottom, and carefully distinguish between the ideas of
sight and touch; which cannot be too oft inculcated in treating of
vision: but more especially throughout the consideration of this affair
we ought to carry that distinction in our thoughts: for that from want of
a right understanding thereof the difficulty of explaining erect vision
seems chiefly to arise.

92. In order to disentangle our minds from whatever prejudices we may
entertain with relation to the subject in hand, nothing seems more
apposite than the taking into our thoughts the case of one born blind,
and afterwards, when grown up, made to see. And though, perhaps, it may
not be an easy task to divest ourselves entirely of the experience
received from sight, so as to be able to put our thoughts exactly in the
posture of such a one's, we must, nevertheless, as far as possible,
endeavour to frame true conceptions of what might reasonably be supposed
to pass in his mind.

93. It is certain that a man actually blind, and who had continued so
from his birth, would by the sense of feeling attain to have ideas of
upper and lower. By the motion of his hand he might discern the situation
of any tangible object placed within his FI reach. That part on which he
felt himself supported, or towards which he perceived his body to
gravitate, he would term lower, and the contrary to this upper; and
accordingly denominate whatsoever objects he touched.

94. But then, whatever judgments he makes concerning the situation of
objects are confined to those only that are perceivable by touch. All
those things that are intangible and of a spiritual nature, his thoughts
and desires, his passions, and in general all the modifications of the