How Shadows and Lights Deceive the Painter's Eye
Curvature deepens shadow, and surrounding tones fool the judgment
Text page of numbered rules for the painter on the depth of shadows. Shadows are darkest on the most curved parts of the limbs and lightest on the broader parts. Two chapters warn how the eye is deceived: a shadow surrounded by weaker (reflected) lights looks less dark than an equal shadow set among strong lights, and a small light in a dark field looks more powerful than an equal light on a bright ground. A closing rule urges the painter always to depict the cause of every dark shadow and reflection, keeping the proportion between lit part and reflection true to the proportion between their light sources.
On this page
Deepest shadow falls on the most curved parts of a limb
The greater or lesser darkness of shadows is generated in the more curved parts of the limbs, and the less dark shadows will be found in the broader, flatter parts.
Equal shadows deceive the eye by their surroundings
Among shadows of equal darkness, the one surrounded by lights of lesser power — such as shadows lying among reflected lights — will appear less dark. The painter is warned not to be misled into altering such a shadow.
A small light in a dark field looks strongest
Among lights of equal brightness, that one will seem most powerful which is smaller and surrounded by a darker field.
Always show the cause of shadow and of reflection
When depicting dark shadows in shadowed bodies, always depict the cause of that darkness, and do the same for reflections; dark shadows are born from dark objects and reflections from objects of little brightness. The proportion of the lit part to the reflection-lit part matches the proportion between the cause of the body's light and the cause of that reflection.