CTESIAS, of Cnidus in Caria, Greek physician and historian, flourished in the 5th century B.C. In early life he was physician to Artaxerxes Mnemon, whom he accompanied (401) on his expedition against his brother Cyrus the Younger. Ctesias was the author of treatises on rivers, and on the Persian revenues, of an account of India and of a history of Assyria and Persia in 23 books, called Persica, written in opposition to Herodotus in the Ionic dialect, and professedly founded on the Persian royal ar chives. The first six books treated of the history of Assyria and Babylon to the foundation of the Persian empire; the remaining 17 went down to the year 398. Of the two histories we possess abridgments by Photius, and fragments in Athenaeus, Plutarch, and especially Diodorus Siculus, whose second book is mainly from Ctesias. As to the worth of the Persica there has been much controversy, both in ancient and modern times. Being based upon Persian authorities, it was naturally looked upon with suspicion by the Greeks and censured as untrustworthy.
For an estimate of Ctesias as a historian see G. Rawlinson's Herodotus, i. 71-74 ; or R W. Macan's Herodotus, vol. ii. Appendix I. 3 5; also the edition of the fragments of the Persica by J. Gilmore (1888, with introduction and notes and list of authorities) .