Medium Shadow and the Brightest Point of a Lit Surface
Where light and shadow mix, the zone of half-shadow, and the strongest light nearest its source
A text page of the Treatise on Painting with an inset geometric diagram, continuing the analysis of light and shade on a body. Leonardo explains that where a shadowed body a b c d is seen by both the light n m and the dark o p its surface mixes light and shadow, and that along the line k h the shadow is of medium darkness. A further section proves the brightest point of an illuminated body (part u c x lit by object a b) lies at c, where the luminous angle a c b is largest. A final heading begins to treat how black bodies show the least difference between their principal shadow and their lights.
On this page
Where light and shadow mix on the surface a b c d
Wherever the surface of a shadowed body is seen by the colors of several objects, their images mingle there. Thus the part a b c d of the shadowed body is mixed with light and shadow, because in that place it is seen by the light n m and by the dark o p.
The zone of medium shadow along line k h
The surface of a shadowed body is of medium brightness and medium shadow where it is equally seen by the bright and the dark. Along the line k h the shadow is as much less dark than the simple primitive shadow c s d as it is less bright than the simple primitive light a r b.
The brightest point lies nearest the illuminating object
The most luminous part of a lit body is the one nearest the object that lights it. Let the lit part be u c x and the illuminating object a b: the point c is more illuminated than any other part, because the luminous angle a c b striking it is larger than any other angle that can be formed on that surface. An inset diagram sets out these lines.
Black bodies: least difference between shadow and light
A closing heading states that the principal shadow of black bodies has the least difference from its principal lights, compared with the surface of any other color. The section breaks off at the page foot to continue overleaf.