A Treatise on Painting
by Leonardo da Vinci, translated by John Francis Rigaud
How the Painter is to place himself in regard to the Light, and his Model
4009422A Treatise on Painting — How the Painter is to place himself in regard to the Light, and his ModelJohn Francis RigaudLeonardo da Vinci

Chap. CLXXXII.How the Painter is to place himself in regard to the Light, and his Model.

Let A B be the window, M the centre of it, C the model. The best situation for the painter will be a little sideways, between the window and his model, as D, so that he may see his object partly in the light and partly in the shadow.