DIOGENES LAERTIUS (or LAERTIUS DIOGENES), the biographer of the Greek philosophers, is supposed by some to have received his surname from the town of Laerte in Cilicia, and by others from the Roman family of the Laertii. Of the circum stances of his life we know nothing. It is probable that he flourished during the reign of Alexander Severus (A.D. 222-235) and his successors. His own opinions are equally uncertain. By some he was regarded as a Christian; but it seems more prob able that he was an Epicurean. The work by which he is known deals with the lives arid sayings of the Greek philosophers. Of no philosophical value itself, its interest lies in the glimpses given of the private life of the philosophers. He treats his subject in two divisions which he describes as the Ionian and the Italian schools. The biographies of the former begin with Anaximander, and end with Cleitomachus, Theophrastus and Chrysippus; the latter begins with Pythagoras, and ends with Epicurus. The Socratic school, with its various branches, is classed with the Ionic ; while the Eleatics and sceptics are treated under the Italic. The whole of the last book is devoted to Epicurus, and contains three most interesting letters addressed to Herodotus, Pythocles and Menoeceus. The text seems once to have been much fuller than that now in existence. In addition to the Lives, Diogenes was the author of a work in verse on famous men, in various metres.
BIBLIOGRAPHY.-Editio princeps (1533) ; H. Hubner and C. Jacobitz Bibliography.-Editio princeps (1533) ; H. Hubner and C. Jacobitz with commentary (1828-33) ; C. G. Cobet (I85o), text only. See F. Nietzsche, "De Diogenis Laertii fontibus" in Rheinisches Museum, xxiii., xxiv. 0868-69) ; J. Freudenthal, "Zu Quellenkunde Diog. Laert.," in Hellenistische Studien, iii. 0879) ; O. Maass, De biographis Graecis (188o) ; V. Egger De fontibus Diog. Laet. (1881). There is an English trans. by C. D. Yonge in Bohn's Class. Lib.