Chap. CCXVIII.—What Part of a Reflex is to be the lightest.
That part will be the brightest which receives the reflected light between angles the most nearly equal. For example, let N be the luminary, and A B the illuminated part of the object, reflecting the light over all the shady part of the concavity opposite to it. The light which reflects upon F will be placed between equal angles. But E at the base will not be reflected by equal angles, as it is evident that the angle E A B is more obtuse than the angle E B A. The angle A F B however, though it is between angles of less quality than the angle E, and has a common base B A, is between angles more nearly equal than E, therefore it will be lighter in F than in E; and it will also be brighter, because it is nearer to the part which gives them light. According to the 6th rule[1], which says, that part of the body is to be the lightest, which is nearest to the luminary.
- ↑ This was intended to constitute a part of some book of Perspective, which we have not; but the rule here referred to will be found in chap. cccx. of the present work.