together in the several ways of
proportion, are by then esteemed entirely disparate and heterogeneous.
Now let anyone try in his thoughts to add a visible line or surface to a
tangible line or surface, so as to conceive them making one continued sum
or whole. He that can do this may think them homogeneous: but he that
cannot, must by the foregoing axiom think them heterogeneous. A blue and
a red line I can conceive added together into one sum and making one
continued line: but to make in my thoughts one continued line of a
visible and tangible line added together is, I find, a task far more
difficult, and even insurmountable: and I leave it to the reflexion and
experience of every particular person to determine for himself.

132. A farther confirmation of our tenet may be drawn from the solution
of Mr. Molyneux's problem, published by Mr. Locke in his ESSAY: which I
shall set down as it there lies, together with Mr. Locke's opinion of it,
'"Suppose a man born blind, and now adult, and taught by his touch to
distinguish between a cube and a sphere of the same metal, and nighly
[SIC] of the same bigness, so as to tell, when he felt one and t'other,
which is the cube and which the sphere. Suppose then the cube and sphere
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