placed on a table, and the blind man to be made to see: QUAERE, whether
by his sight, before he touched them, he could now distinguish and tell
which is the globe, which the cube?" To which the acute and judicious
proposer answers: "Not. For though he has obtained the experience of how
a globe, how a cube, affects his touch, yet he has not yet attained the
experience that what affects his touch so or so must affect his sight so
or so: or that a protuberant angle in the cube that pressed his hand
unequally shall appear to his eye as it doth in the cube." I agree with
this thinking gentleman, whom I am proud to call my friend, in his answer
to this his problem; and am of opinion that the blind man at first sight
would not be able with certainty to say which was the globe, which the
cube, whilst he only saw them.' (ESSAY ON HUMAN UNDERSTANDING, B. ii. C.
9. S. 8.)

133. Now, if a square surface perceived by touch be of the same sort with
a square surface perceived by sight, it is certain the blind man here
mentioned might know a square surface as soon as he saw it: it is no more
but introducing into his mind by a new inlet an idea he has been already
well acquainted with. Since, therefore, he is supposed to have known by
his touch that a cube is a body terminated by square surfaces, and that a
sphere is not terminated by square surfaces: upon the supposition that a
visible and tangible square differ only IN NUMERO it follows that he
might know, by the unerring mark of the square surfaces, which was the
cube, and which not, while he only saw them. We must therefore allow
either that visible extension and figures are specifically distinct from
tangible extension and figures, or else that the solution of this problem
given by those two thoughtful and ingenious men is wrong.

134. Much more might be laid together in proof of the proposition I have
advanced: but what has been said is, if I mistake not, sufficient to