g any other IDEA. If I do not perceive the
redness or paleness of a man’s face themselves, it is impossible I should
perceive by them the passions which are in his mind.
11. Now from sect. 2 it is plain that distance is in its own nature
imperceptible, and yet it is perceived by sight. It remains, therefore,
that it be brought into view by means of some other IDEA that is itself
immediately perceived in the act of VISION.
12. But those LINES and ANGLES, by means whereof some MATHEMATICIANS
pretend to explain the perception of distance, are themselves not at all
perceived, nor are they in truth ever thought of by those unskilful in
optics. I appeal to anyone’s experience whether upon sight of an OBJECT he
computes its distance by the bigness of the ANGLE made by the meeting of
the two OPTIC AXES? Or whether he ever thinks of the greater or lesser
divergency of the rays, which arrive from any point to his PUPIL? Everyone
is himself the best judge of what he perceives, and what not. in vain
shall all the M