Leucippus and Democritus ( 5th century BC and [ 460-370 BC])

LEUCIPPUS AND DEMOCRITUS

Leucippus and Democritus were the earliest Greek atomists. The originator of the atomic theory, Leucippus (fifth century BCE), must be considered a speculative thinker of the first order, but to Democritus (c. 460–c. 370 BCE) must go the credit for working out the detailed application of the theory and supporting it with a subtle epistemology. Moreover, the range of Democritus's researches surpassed that of any earlier philosopher, and he appears to have been an original and, for his day, advanced ethical thinker.

We have very little biographical data for Leucippus. Epicurus is even reported to have said that there was no philosopher Leucippus, but the evidence of Aristotle decisively refutes this opinion (if, indeed, Epicurus did not merely intend to deny Leucippus's philosophical importance). Leucippus was probably born at Miletus; reports associating him with Elea or Abdera should be taken as reflecting views concerning his philosophical affiliations rather than as reliable evidence for his birthplace. He was presumably older than Democritus. His book On Mind may have been directed partly against Anaxagoras, and according to Theophrastus, Diogenes of Apollonia derived some of his theories from Leucippus. All this suggests that Leucippus was a slightly younger contemporary of Anaxagoras and that his main philosophical activity fell some time within the broad limits of 450–420 BCE.

Democritus was born at Abdera. He described himself in the Little World-System as a young man in the old age of Anaxagoras; Diogenes Laërtius says that he was forty years younger than Anaxagoras. On this evidence the date given for his birth by Apollodorus (in the 80th Olympiad, 460–456 BCE) is generally preferred to that suggested by Thrasylus (the third year of the 77th Olympiad, 470–469 BCE). He is variously reported to have lived between 90 and 109 years. To judge from the number of his writings, his literary activity extended over a considerable period, but we have no means of assigning different works to different times in his life. His statement that he wrote the Little World-System 730 years after the fall of Troy (Diogenes Laërtius, Lives IX, 41) is of little value since we cannot tell which of several possible chronologies for the Trojan War Democritus accepted.

Many stories, most of them apocryphal, relating to Democritus's life and character circulated in antiquity. There are the accounts of his saving the Abderites from a plague, of his dying by voluntarily abstaining from food, and of his reputation as the "Laughing Philosopher." The tradition that he traveled extensively is, however, more plausible and better grounded. The authenticity of the fragment (299) in which he claimed to be the most widely traveled of his contemporaries is disputed, and the genuineness of the five books dealing with foreign travel mentioned by Diogenes Laërtius (for example, A Voyage round the Ocean ) has also been doubted. But evidence concerning his travels goes back to Theophrastus (see Aelian, Varia Historia IV, 20), and the reports that he visited such places as Egypt, Chaldea, and the Red Sea (see Diogenes Laërtius, Lives IX, 35) may well have a sound basis in fact.

All that has been preserved of the original writings of Leucippus and Democritus is a poor selection of isolated quotations, most of which derive from the ethical works of Democritus. For the atomic theory itself we rely on reports in Aristotle, Theophrastus, and later doxographers, who were often unsympathetic to the views of the atomists. In most of the principal texts referring to Leucippus, his doctrines are not clearly distinguished from those of Democritus, and the precise contribution of each philosopher is in question. Aristotle, however, undoubtedly treated Leucippus as the founder of atomism (De Generatione et Corruptione 325a23ff.), and we may reasonably attribute both the principles of the physical theory and a fairly complex cosmogony to him. Democritus evidently elaborated the atomic theory and was responsible for the detailed account of sensible qualities, besides going far beyond Leucippus both in the range of his scientific inquiries and in his interest in moral philosophy.

Writings

Only two works are ascribed to Leucippus, On Mind, from which our sole surviving quotation comes, and the Great World-System, which may be attributed to Leucippus on the authority of Theophrastus (Diogenes Laërtius, Lives IX, 46), although Thrasylus later assigned it to Democritus.

Democritus, on the other hand, wrote some sixty-odd works, the titles of which provide valuable evidence of the scope of his interests. The main works were cataloged by Thrasylus into thirteen tetralogies. Two tetralogies are devoted to ethics and four to physics (includingLittle World-System, On the Planets, On Nature, On the Nature of Man, On the Senses, and On Colors ). These were followed by nine works not arranged in tetralogies—for example, Causes of Celestial Phenomena, Causes concerning Seeds, Plants and Fruits, and three books of Causes concerning Animals. …