Democritus, probably the greatest of the Greek physical philosophers, was a native of Abdera in Thrace, or as some say -- probably wrongly -- of Miletus.
Our knowledge of his life is based almost entirely on tradition of an untrustworthy kind. He seems to have been born about 470 or 460 BC, and was, therefore, an older contemporary of Socrates. He inherited a considerable property, which enabled him to travel widely in the East in search of information. In Egypt he settled for seven years, during which he studied the mathematical and physical systems of the ancient schools. The extent to which he was influenced by the Magi and the Eastern astrologists is a matter of pure conjecture. He returned from his travels impoverished; one tradition says that he received 500 talents from his fellow citizens, and that a public funeral was decreed him. Another tradition states that he was regarded as insane by the Abderitans, and that Hippocrates was summoned to cure him. Diodorus Siculus tells us that he died at the age of ninety; others make him as much as twenty years older. His works, according to Diogenes Laërtius, numbered seventy-two, and were characterized by a purity of style which compares favorably with that of Plato. The absurd epithet, the "laughing philosopher", applied to him by some unknown and very superficial thinker, may possibly have contributed in some measure to the fact that his importance was for centuries overlooked. It is interesting, however, to notice that Bacon (De Principiis) assigns to him his true place in the history of thought, and points out that both in his own day and later "in the times of Roman learning" he was spoken of in terms of the highest praise. In the variety of his knowledge, and in the importance of his influence on both Greek and modern speculation he was the Aristotle of the 5th century, while the sanity of his metaphysical theory has led many to regard him as the equal, if not the superior, of Plato.