DIOGENES LAERTIUS, 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 circumstances of his life we know nothing. The date at which he wrote—probably the reign of Septimius Severus (193-211)—is known only from conjecture. His own opinions are equally uncertain. By some he was regarded as a Christian; but it seems more probable that he was an Epicurean. The work by which he is known professes to give an account of the liγβs and sayings of the Greek philosophers. Although it is at best an uncritical and unphilosophical compilation, its value, as giving us an insight into the private life of the Greek sages, justly led Montaigne to exclaim that he wished that instead of one Laertius there had been a dozen. In the commencement of the work he divides philosophers into the Ionic and Italic schools. The biographies of the former begin with Anaximander, and end with Clitomachus, 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. From the statements of Burlaeus, the text of Laertius seems to have been much fuller than that which we now possess; and hopes have been entertained of obtaining a more complete copy.

The best modern edition is that of Hübner, Leipsic, 2 vols. 8vo, 1828-31.