Leucippus, << loo KIHP uhs, >> was a Greek philosopher who lived in the 400’s B.C. Leucippus originated the theory of atomism. His atomic theory states that matter is composed of fundamental particles, or atoms. These particles cannot be further divided. The term atom comes from the Greek word atomos, meaning uncuttable.
Unlike earlier Greek philosophers, Leucippus believed that what is (atoms) and what is not (empty space) are both real. He believed that all observable properties of an object result from the movement and collision of atoms in empty space. Leucippus thought that this behavior of atoms was completely determined in advance. “Everything,” Leucippus wrote, “comes about for a reason and by necessity.”
Little is known of Leucippus’ life, and only one fragment of his writings has survived. His ideas, however, have come down to us through the work of his pupil Democritus.
