DICAEARCHUS, of Messene in Sicily, Peripatetic philosopher and pupil of Aristotle, historian, and geographer, flourished about 320 B.C. He was a friend of Theophrastus, to whom he dedicated the majority of his works. Of his writings, which comprised treatises on a great variety of subjects, only the titles and a few fragments survive. The most important of them was his βίος τῆς Έλλάδος (Life in Greece), in which the moral, political and social condition of the people was very fully discussed. In his Tripoliticos he described the best form of government as a mixture of monarchy, aristocracy and democracy, and illustrated it by the example of Sparta. Among the philosophical works of Dicaearchus may be mentioned the Lesbiaci, a dialogue in three books, in which the author endeavours to prove that the soul is mortal, to which he added a supplement called Corinthiaci. He also wrote a Description of the World illustrated by maps, in which was probably included his Measurements of Mountains. A description of Greece (150 iambics, in C. Müller, Frag. hist. Graec. i. 238-243) was formerly attributed to him, but, as the initial letters of the first twenty-three lines show, was really the work of Dionysius, son of Calliphon. Three considerable fragments of a prose description of Greece (Müller, i. 97-110) are now assigned to an unknown author named Heracleides. The De re publica of Cicero is supposed to be founded on one of Dicaearchus’s works.
The best edition of the fragments is by M. Fuhr (1841), a work of great learning; see also a dissertation by F. G. Osann, Beiträge zur röm. und griech. Litteratur, ii. pp. 1-117 (1839); Pauly-Wissowa, Realencyclopädie der klass. Altertumswiss. v. pt. 1 (1905).