A Treatise on Painting/Chapter 196
Chap. CXCVI.—How to give Grace and Relief to Faces.
In streets running towards the west, when the sun is in the meridian, and the walls on each side so high that they cast no reflexions on that side of the bodies which is in shade, and the sky is not too bright, we find the most advantageous situation for giving relief and grace to figures, particularly to faces; because both sides of the face will participate of the shadows of the walls. The sides of the nose and the face towards the west, will be light, and the man whom we suppose placed at the entrance, and in the middle of the street, will see all the parts of that face, which are before him, perfectly illumined, while both sides of it, towards the walls, will be in shadow. What gives additional grace is, that these shades do not appear cutting, hard, or dry, but softly blended and lost in each other. The reason of it is, that the light which is spread all over in the air, strikes also the pavement of the street, and reflecting upon the shady part of the face, it tinges that slightly with the same hue: while the great light which comes from above being confined by the tops of houses, strikes on the face from different points, almost to the very beginning of the shadows under the projecting parts of the face. It diminishes by degrees the strength of them, increasing the light till it comes upon the chin, where it terminates, and loses itself, blending softly into the shades on all sides. For instance, if such light were A E, the line F E would give light even to the bottom of the nose. The line C F will give light only to the under lip; but the line A H would extend the shadow to all the under parts of the face, and under the chin.
In this situation the nose receives a very strong light from all the points A B C D E.
