Of trees seen from below and against the light, one beyond the other
and near together. The topmost part of the first will be in great
part transparent and light, and will stand out against the dark
portion of the second tree. And thus it will be with all in
succession that are placed under the same conditions.

Let _s_ be the light, and _r_ the eye, _c d n_ the first tree, _a b
c_ the second. Then I say that _r_, the eye, will see the portion _c
f_ in great part transparent and lighted by the light _s_ which
falls upon it from the opposite side, and it will see it, on a dark
ground _b c_ because that is the dark part and shadow of the tree _a
b c_.

But if the eye is placed at _t_ it will see _o p_ dark on the light
background _n g_.

Of the transparent and shadowy parts of trees, that which is nearest
to you is the darkest.