Professor Lange remarks, however, that “he cites him, for the most part, only when he attacks him, and this he by no means always does with a fitting objectivity and fairness. How often he has borrowed from him without naming him we do not know. Plato speaks of him nowhere, though it is a matter of dispute whether, in some places, he has not controverted his opinion without mention of his name” (“History of Materialism,” page 18). It seems to be quite possible that Plato knew little or nothing of the writing of Democritus. At any rate, they were not well known in Athens before Aristotle’s discussion of his theories. An extant Democritean fragment states that “I went to Athens and no one knew me.” Professor Burnet says: “It is not clear that Plato knew anything about Democritus, for the few passages in the Timæus and elsewhere where he seems to be reproducing him are easily explained by the Pythagorean influences that affected them both. Aristotle, on the other hand, knows Democritus well; for he too was an Ionian from the north. “It is certain, nevertheless, that the Democritean corpus (which included the works of Leucippus and others as well as those of Democritus) continued to exist; for the school maintained itself at Abdera and Teos down to Hellenistic times. It was therefore possible for Thrasyllos in the reign of Tiberius to produce an edition of the works of Democritus arranged in tetralogies just like his edition of Plato’s dialogues. Even that did not suffice to preserve them.”[8] Besides being the favorite pupil of Leucippus, Democritus (according to Glaubus of Rhegion, a contemporary) had also Pythagoreans for teachers, including the astronomer, geometrician and physician, Philolaus, who was exiled from Italy in the first half of the fifth century B. C. because of his membership in the Pythagorean Order. Burnet thinks that this accounts not only for Democritus’ geometrical knowledge but also “for other features of his system.” THE PHYSICS OF DEMOCRITUS We know that both Leucippus and Democritus regarded the atoms composing the various substances of the world as being homogeneous--i.e., all alike from a chemical stand-point, but differing from one another in point of size and in rich variety of form. Unlike the minute particles (homœomeries) of Anaxagoras, which were assumed to be infinitely divisible as well as qualitatively different for each substance, the atoms of Leucippus and Democritus were considered indivisible; hence the name _atoma_ (atoms) (particles which cannot be cut, or further divided).