...[the surroundings] will make the face appear with the true lights and shades of its flesh, and this method is most useful for making flesh appear most beautiful; but such a precept is contrary to the precepts for figures set in a landscape ringed by diverse colours, for a figure then placed in such a landscape would be against the 3rd [proposition] of the 9th [book] of this [work].

[710]1 a. Of the shadows of faces that, passing along wet streets, do not appear to match their own flesh-tones. Book A, sheet 47.

What is asked here occurs because often a face may be coloured or pale while its shadows turn yellowish; and this happens because wet streets are more yellow than dry ones, and the parts of the face turned toward such streets are tinted with the yellowness and darkness of the streets that stand before them as their object.

[711]2 b. Of the quality of the air upon shadows and lights.

That body will make the greater difference between its shadows and its lights which is seen by a greater light, such as the light of the sun, or at night the light of a fire; and this is little to be used in painting, because the works remain crude and without grace.

That body which is in moderate light will have little difference between its lights and its shadows; and this occurs toward evening, or when it is cloudy; and these works are soft, and every kind of face has grace in them, so that in everything the extremes are faulty: too much light makes it crude, too much dark does not let it be seen; the middle is good.