A Treatise on Painting/Chapter 203
Chap. CCIII.—Of the Eye viewing the Folds of Draperies surrounding a Figure.
The shadows between the folds of a drapery surrounding the parts of the human body will be darker as the deep hollows where the shadows are generated are more directly opposite the eye. This is to be observed only when the eye is placed between the light and the shady part of the figure.