the light is of the same form and size as the body causing the shadow.
The derived shadow cannot be of the same form as the primary shadow unless it is intercepted by a plane parallel to it.
164.
HOW A CAST SHADOW CAN NEVER BE OF THE SAME SIZE AS THE BODY THAT CASTS IT.
If the rays of light proceed, as experience shows, from a single point and are diffused in a sphere round this point, radiating and dispersed through the air, the farther they spread the wider they must spread; and an object placed between the light and a wall is always imaged larger in its shadow, because the rays that strike it [Footnote: 7. The following lines are wanting to complete the logical connection.] would, by the time they have reached the wall, have become larger.
165.
Any shadow cast by a body in light and shade is of the same nature and character as