MEDIUM whereby the mind judgeth of distance in those cases wherein the
most approved writers of optics will have it judge by the different
divergency with which the rays flowing from the radiating point fall on
the PUPIL. No man, I believe, will pretend to see or feel those imaginary
angles that the rays are supposed to form according to their various
inclinations on his eye. But he cannot choose seeing whether the OBJECT
appear more or less confused. It is therefore a manifest consequence from
what bath been demonstrated, that instead of the greater or lesser
divergency of the rays, the mind makes use of the greater or lesser
confusedness of the appearance, thereby to determine the apparent place
of an OBJECT.

23 Nor doth it avail to say there is not any necessary connection between
confused VISION and distance, great or small. For I ask any man what
necessary connection he sees between the redness of a blush and shame? And
yet no sooner shall he behold that colour to arise in the face of
another, but it brings into his and the IDEA of that passion which hath
been observed to accompany it.

24. What seems to have misled the writers of optics in this matter is
that they imagine men judge of distance as they do of a conclusion in
mathematics, betwixt which and the premises it is indeed absolutely
requisite there be an apparent, necessary connection: but it is far
otherwise in the sudden judgments men make of distance. We are not to
think that brutes and children, or even grown reasonable men, whenever
they perceive an OBJECT to approach, or depart from them, do it by virtue
of GEOMETRY and DEMONSTRATION.

25. That one IDEA may suggest another to the mind it will suffice that
they have been observed to go together, without any demonstration of the