Shadows That Shrink, and Shadows Unchanged by Distance
A larger light shortens the shadow with nearness; an equal light leaves it constant
The page completes the converse rule: when the luminous body a b is larger than the object x y r h, the shadow diminishes as the object approaches, because the rays embrace it beyond its middle. Leonardo then proves a third case: when light and opaque body are of equal size, no distance or nearness changes the shadow at all, since the embracing rays run parallel. A fourth proposition opens, that among equal bodies the one lit by the larger light casts the shorter shadow.
On this page
A larger light shortens the shadow as the body approaches
Let a b be the luminous body, larger than the shadowed body x y r h; drawing near to the light at c e o d, it diminishes its shadow, because near the illuminating body the rays embrace it beyond its middle, more than when it was distant. The upper diagram shows the object touched by rays that reach past its equator.
Equal light and body: the shadow neither grows nor shrinks
When the shadowed and luminous bodies are equal in size, no distance interposed between them can change their shadowed or lit parts. Let n m be the shadowed body drawn to position c d nearer the light a b: the quantity of its shadow is unchanged, because the luminous rays that embrace it are in themselves parallel.