In consequence of the conclusion [shown] in the above diagram, t will be less darkened than v , because the base of the t is part of the base of the v ; and in the same way it follows that p is less in shadow than t , because the base of the p is part of the base of the t . And c is the terminal point of the derived shadow and the chief beginning of the highest light.
[Footnote: The diagram on Pl. IV, No. 5 belongs to this passage; but it must be noted that the text explains only the figure on the right-hand side.]
FOURTH BOOK ON LIGHT AND SHADE.
On the shape of the cast shadows (188-191).
188.
The form of the shadow cast by any body of uniform density can never be the same as that of the body producing it.