Chapter Xv. of Colors.

Color is the visible quality of a body.

The Pythagoreans called color the external appearance of a body. Empedocles, that which is consentaneous to the passages of the eye. Plato, that they are fires emitted from bodies, which have parts harmonious for the sight. Zeno the Stoic, that colors are the first figurations of matter. The Pythagoreans, that colors are of four sorts, white and black, red and pale; and they derive the variety of colors from the mixtures of the elements, and that seen in animals also from the variety of food and the air.