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.
CHAPTER XVI. OF THE DIVISION OF BODIES.
The disciples of Thales and Pythagoras grant that all bodies are passible and divisible into infinity. Others hold that atoms and indivisible parts are there fixed, and admit not of a division into infinity. Aristotle, that all bodies are potentially but not actually divisible into infinity.
CHAPTER XVII. HOW BODIES ARE MIXED AND CONTEMPERATED ONE WITH ANOTHER.
The ancient philosophers held that the mixture of elements proceeded from the alteration of qualities; but the disciples of Anaxagoras and Democritus say it is done by apposition. Empedocles composes the elements of still minuter bulks, those which are the most minute and may be termed the element of elements. Plato assigns three bodies (but he will not allow these to be elements, nor properly so called), air, fire, and water, which are mutable into one another; but the earth is mutable into none of these.
CHAPTER XVIII. OF A VACUUM.
All the natural philosophers from Thales to Plato rejected a vacuum. Empedocles says that there is nothing of a vacuity in Nature, nor anything superabundant. Leucippus, Democritus, Demetrius, Metrodorus, Epicurus, that the atoms are in number infinite; and that a vacuum is infinite in magnitude. The Stoics, that within the compass of the world there is no vacuum, but beyond it the vacuum is infinite. Aristotle, that the vacuum beyond the world is so great that the heaven has liberty to breathe into it, for the heaven is fiery.