The forms of shadows are three: inasmuch as if the solid body which
casts the shadow is equal (in size) to the light, the shadow
resembles a column without any termination (in length). If the body
is larger than the light the shadow resembles a truncated and
inverted pyramid, and its length has also no defined termination.
But if the body is smaller than the light, the shadow will resemble
a pyramid and come to an end, as is seen in eclipses of the moon.
161.