forms, and elements too have forms.
Now a body, says Apollodorus in his Natural Philosophy, is extended in a threefold manner; in length, in breadth, in depth; and then it is called a solid body; and the superficies is the limit of the body having length and breadth alone, but not depth. But Posidonius, in the third book of his Heavenly Phænomena, will not allow a superficies either any substantial reality, or any intelligible existence. A line is the limit of a superficies, or length without breadth, or something which has nothing but length. A point is the boundary of a line, and is the smallest of all symbols.
They also teach that God is unity, and that he is called Mind, and Fate, and Jupiter, and by many other names besides. And that, as he was in the beginning by himself, he turned into water the whole substance which pervaded the air; and as the seed is contained in the produce, so too, he being the seminal principle of the world, remained behind in moisture, making matter fit to be employed by himself in the production of those things which were to come after; and then, first of all, he made the four elements, fire, water, air, and earth. And Zeno speaks of these in his treatise on the Universe, and so does Chrysippus in the first book of his Physics, and so does Archedemus in some treatise on the Elements.
LXIX. Now an element is that out of which at first all things which are are produced, and into which all things are resolved at last. And the four elements are all equally an essence without any distinctive quality, namely, matter; but fire is the hot, water the moist, air the cold, and earth the dry—though this last quality is also common to the air. The fire is the highest, and that is called æther, in which first of all the sphere was generated in which the fixed stars