Dicaearchus of Messina

(fl. 310 b.c.).

Dicaearchus was a distinguished disciple of Aristotle and the author of many books in different fields, none of which is preserved, so that our knowledge of them is fragmentary and often problematical.

On the Soul, six books in dialogue form, espoused the view that the soul is “nothing,” immaterial, merely a condition of the body, a “harmony of the four elements”—and consequently perishable and not immortal. The doctrine was not new, but this exposition of it was one of the best. Descent Into the Cave of Trophonius, also a dialogue, belittled oracles and recognized only dreams and inspirations as valid sources of prophecy. The same view is attributed to Aristotle. Tripoliticus, a dialogue on political theory, advocated a composite constitution, combining the three traditional types of government: monarchy, aristocracy, and democracy. It seems that Dicaearchus saw this exemplified in Sparta, a state to which he was partial. The idea of a mixed constitution was taken up by Polybius. The Life of Greece, in three books, dealt with anthropological, moral, and cultural history, including the primitive and the Oriental forerunners of Greek civilization. The work was significant for extending history, on Peripatetic principles, over fields other than the political and military. It was the model for a work by Varro on the Romans.

Dicaearchus’ only work on natural science was a geography, Tour of the Earth, following the work of Eudoxus of Cnidus. These two were the first geographers to combine the actual knowledge of lands and seas with the theory of the earth as a sphere, which by then was generally accepted. Measuring a long arc north from Syene (Aswan) and observing the zenith points at the ends, they calculated the circumference to be 400,000 or 300,000 stades (stades varied from 148 to 198 meters). The area of the world then known proved to be only a small part of the surface of the sphere, perhaps 45,000 stades by 30,000 stades. Dicaearchus defended the theory of the earth as a sphere by “measuring” the highest mountains, which he found to be only ten or fifteen stades high, showing that they were insignificant in relation to the curvature of the sphere. Within the known world he sought to schematize the masses of land and sea and mountains—without the aid, of course, of specific latitude, much less of longitude. His successor in this field was Eratosthenes, whose great improvements were practical rather than theoretical.

Among the disciples of Aristotle, Dicaearchus and Aristoxenus of Tarentum, another Dorian from the west, seem to have been particularly congenial, while there was some antipathy between Dicaearchus and Theophrastus, the head of the Peripatetic school. Dicaearchus saw the purpose of knowledge as practical action; Theophrastus, as theoretical contemplation. Among posterity Cicero and Atticus were admirers of Dicaearchus and used his works extensively.

BIBLIOGRAPHY

Additional information may be found in Edgar Martini, “Dikaiarchos 3. Peripatetiker,” in Pauly-Wissowa, V, pt. 1 (1903), 546–563; and Fritz Wehrli, Die Schule des Aristoteles, Texte und Kommentar, Heft I, Dikaiarchos (Basel, 1944; 2nd ed., rev. and enl., 1967).

Aubrey Diller