OF PAINTING.

Of different shadows of equal strength that which is nearest the eye
will seem the least strong.

Why is the shadow _e a b_ in the first grade of strength, _b c_ in
the second; _c d_ in the third? The reason is that as from _e a b_
the sky is nowhere visible, it gets no light whatever from the sky,
and so has no direct [primary] light. _b c_ faces the portion of the
sky _f g_ and is illuminated by it. _c d_ faces the sky at _h k_. _c
d_, being exposed to a larger extent of sky than _b c_, it is
reasonable that it should be more lighted. And thus, up to a certain
distance, the wall _a d_ will grow lighter for the reasons here
given, until the darkness of the room overpowers the light from the
window.