and artificial perspective. By natural perspective I mean that the
plane on which this perspective is represented is a flat surface,
and this plane, although it is parallel both in length and height,
is forced to diminish in its remoter parts more than in its nearer
ones. And this is proved by the first of what has been said above,
and its diminution is natural. But artificial perspective, that is
that which is devised by art, does the contrary; for objects equal
in size increase on the plane where it is foreshortened in
proportion as the eye is more natural and nearer to the plane, and
as the part of the plane on which it is figured is farther from the
eye.

And let this plane be _d e_ on which are seen 3 equal circles which
are beyond this plane _d e_, that is the circles _a b c_. Now you
see that the eye _h_ sees on the vertical plane the sections of the
images, largest of those that are farthest and smallest of the
nearest.

108.

Here follows what is wanting in the margin at the foot on the other
side of this page.

Natural perspective acts in a contrary way; for, at greater
distances the object seen appears smaller, and at a smaller distance
the object appears larger. But this said invention requires the
spectator to stand with his eye at a small hole and then, at that
small hole, it will be very plain. But since many (men's) eyes
endeavour at the same time to see one and the same picture produced
by this artifice only one can see clearly the effect of this