Transparent Shadows and the Principal Shadow of a Limb
Shadows of translucent bodies, leaves, and the master shadow between incident and reflected light
This text-only page completes the proof that a sphere resting on the earth casts the darkest shadow, invoking the maxim that every effect partakes of its cause. It then treats the shadows of somewhat transparent bodies, noting that translucent things (such as tree leaves) cast a dark shadow only where many overlap. A further section describes the 'principal' or master shadow lying between incident and reflected light on a limb, which has no sharp cut-off and varies in edge, straightness and breadth, a subject Leonardo says deserves its own book. A final heading opens the theme of outlines that first lose their distinctness.
On this page
The sphere on the earth casts the deepest shadow
By the principle that every effect partakes of its cause, the earth, being darker in itself, gives the sphere resting on it a darker shadow. The shaded surface being darker than the illuminated one, the point is concluded.
Transparent bodies shadow only when overlapping
No body partaking of transparency casts a dark shadow unless shaded by the darkness of many other similar bodies' shadows, as with the leaves of trees, which cast their shadows one upon another.
The master shadow between incident and reflected light
The principal shadow interposed between reflected and incident light is not cut off and ends only with the limb it rests on; its sides lie at varying distances from its middle, sometimes with defined and sometimes with imperceptible edges. Leonardo notes that of this discourse a whole book should be composed.