DICAeARCHUS, a celebrated Peripatetic philosopher, historian, and geographer, was a native of Messana, in Sicily. He was the contemporary of Theophrastus and Aristotle, and flourished towards the close of the 4th century b.c. The exact dates of his birth and death are unknown; the time of the latter event is approximately fixed by good authorities as the year 285 b.c. Nothing is known with certainty concerning the life óf Dicaearchus except that he was a disciple of Aristotle and 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, none have descended to our day. Nothing but their titles and a few fragments survive. The most important of them was his Life in Greece, in which the moral, political, and social condition of the people was very fully discussed. Among the philosophical works of Dicaearchus may be mentioned the Lesbiaci, in three books, in which the author endeavours to prove that the soul is mortal. This work is written in the form of a dialogue, and derived its name from the fact that the scene of the dialogue was laid at Lesbos. To it the author afterwards appended a supplement, likewise in three books, which he called Corinthiaci. The only complete edition of the fragments of Dicaearchus is that published at Darmstadt in 1841 by Max Fuhr. An excellent dissertation on them will be found in Osann, Beiträge zur Griech. und Rom. Literatur.