ONESICRITUS, or Onesicrates, of Aegina or Astypaleia (probably simply the “old city” of Aegina), one of the writers on Alexander the Great. At an advanced age he became a pupil of Diogenes the Cynic, and gained such repute as a student of philosophy that he was selected by Alexander to hold a conference with the Indian Gymnosophists. When the fleet was constructed on the Hydaspes, Onesicritus was appointed chief pilot (in his vanity he calls himself commander), and in this capacity accompanied Nearchus on the voyage from the mouth of the Indus to the Persian gulf. He wrote a diffuse biography of Alexander, which in addition to historical details contained descriptions of the countries visited, especially India. After the king’s death, Onesicritus appears to have completed his work at the court of Lysimachus, king of Thrace. Its historical value was considered small, it being avowedly a panegyric, and contemporaries (including even Alexander himself) regarded it as untrustworthy. Strabo especially takes Onesicritus to task for his exaggeration and love of the marvellous. His Paraplus (or description of the coasts of India) probably formed part of the work, and, incorporated by Juba II. of Mauretania with the accounts of coasting voyages by Nearchus and other geographers, and circulated by him under the name of Onesicritus, was largely used by Pliny.

See Arrian, Anabasis, vi. 2; Indica, 32; Diogenes Laërtius vi. 75; Plutarch, Alexander, 46, 65; Strabo xv. 698; Pliny, Nat. Hist. vi. 26; Aulus Gellius ix. 4; fragments and life in C. W. Müller, appendix to F. Dübner’s Arrian (1846); monograph by F. Lilie (Bonn, 1864); E. H. Bunbury, Hist. of Ancient Geography, i. (1879); Meier in Ersch and Gruber’s Allgemeine Encyclopädie.