Perspective of solar rays.

a sun - d o p c r s t - b f g h i K L m c - water

The solar rays reflected from the surface of wavy water make the image of the sun appear continuous over all that water which lies between the universe and the sun.

It is proved. Let a be the body of the sun, b c the surface of the wavy water, d t the universe that this water sees between itself and the sun. By the second [proposition] of the first [book], the image of the sun that comes from the sun to the wave m necessarily reflects to t and nowhere else. And likewise the image of the sun that comes from the sun to f rebounds to [d] and nowhere else. And so does each wave set between these two extremes; whence necessarily the whole line d t, set opposite such images, is seen and lit by all those images, where the reflected rays spread out; and at some distance it will be discontinuous in splendour, as will here be shown.

a c b d sun - e f

The image that is reflected from the wave to the object gains width at every degree of length.

The image f rebounds in c d, and the image of the wave e rebounds in a b. These two strikings of reflected rays superimpose upon one another reciprocally in c b, and there the light is twice as luminous as in a c or b d.