confirmed and riveted in our thoughts by a long tract of time, by the use
of language, and want of reflexion. However, I believe anyone that shall
attentively consider what we have already said, and shall say, upon this
subject before we have done (especially if he pursue it in his own
thoughts) may be able to deliver himself from that prejudice. Sure I am
it is worth some attention, to whoever would understand the true nature
of vision.

52. I have now done with distance, and proceed to show how it is that we
perceive by sight the magnitude of objects. It is the opinion of some
that we do it by angles, or by angles in conjunction with distance: but
neither angles nor distance being perceivable by sight, and the things we
see being in truth at no distance from us, it follows that as we have
shown lines and angles not to be the medium the mind makes use of in
apprehending the apparent place, so neither are they the medium whereby
it apprehends the apparent magnitude of objects.

53. It is well known that the same extension at a near distance shall
subtend a greater angle, and at a farther distance a lesser angle. And by
this principle (we are told) the mind estimates the magnitude of an
object, comparing the angle under which it is seen with its distance, and
thence inferring the magnitude thereof. What inclines men to this mistake
(beside the humour of making one see by geometry)is that the same
perceptions or ideas which suggest distance do also suggest magnitude.
But if we examine it we shall find they suggest the latter as immediately
as the former. I say, they do not first suggest distance, and then leave
it to the judgment to use that as a medium whereby to collect the
magnitude; but they have as close and immediate a connexion with the
magnitude as with the distance; and suggest magnitude as independently of
distance as they do distance independently of magnitude. All which will