c.460-c.370 B.C., Greek philosopher. His atomic theory of the nature of the
physical world, known to us through Aristotle's writings, was the most scientific theory proposed up to his Time. He held that all living things are composed of tiny indivisible particles,
called Atoms, and that their constant Motion explains the creation of the universe: the heavier atoms clustered together
to form the earth, while the lighter ones formed the heavenly bodies.