- For the beetle genus, see Ctesias (beetle).
Ctesias of Cnidus (pron.: //; Ancient Greek: Κτησίας) was a Greek physician and historian from Cnidus in Caria. Ctesias, who lived in the 5th century BC, was physician to Artaxerxes Mnemon, whom he accompanied in 401 BC 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 entitled Indica (which is of value as recording the beliefs of the Persians about 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 archives.
The first six books covered the history of Assyria and Babylon to the foundation of the Persian empire; the remaining seventeen went down to the year 398 BC. Of the two histories, we possess abridgments by Photius, and fragments are preserved in Athenaeus, Plutarch, Nicholas of Damascus 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. Although many ancient authorities valued it highly, and used it to discredit Herodotus, a modern author writes that "(Ctesias's) unreliability makes Herodotus seem a model of accuracy." Ctesias's account of the Assyrian kings does not reconcile with the cuneiform evidence. The satirist Lucian thought so little of Ctesias' historical reliability that in his satirical True Story he places Ctesias on the island where the evil were punished. Lucian wrote that "The people who suffered the greatest torment were those who had told lies when they were alive and written mendacious histories; among them were Ctesias of Cnidus, Herodotus, and many others."
A record of the view of Persians of India, under the title Indica includes descriptions of god like people, philosophers, artisans, unquantifiable gold, among other riches and wonders. The book only remains in fragments and in reports made about the book by later authors.
- This article incorporates text from a publication now in the public domain: Chisholm, Hugh, ed. (1911). Encyclopædia Britannica (11th ed.). Cambridge University Press.
- Burn A.R. Persia and the Greeks. Duckworth. London. 1984. As quoted by Peter Frederick Barker, FROM THE SCAMANDER TO SYRACUSE. STUDIES IN ANCIENT LOGISTICS, page 9, chapter 1. http://uir.unisa.ac.za/bitstream/handle/10500/1740/00dissertation.pdf?sequence=2
- Lucian, A True Story, 2.31
- Lavers, Chris (2009). The Natural History of Unicorns. New York, NY: Morrow. p. 5. ISBN 978-0-06-087414-8.
Further reading 
- Ed., trad. et commentaire par Dominique Lenfant, Ctésias de Cnide. La Perse. L'Inde. Autres fragments, Collection Budé, Belles Lettres, Paris, 2004 (ISBN 2251005188).
- Jan P. Stronk: Ctesias' Persian History. Part I: Introduction, Text, and Translation, Wellem Verlag, Düsseldorf, 2010 (ISBN 9783941820012).
- Andrew G. Nichols, Ctesias: On India. Translation and Commentary, Duckworth, 2011, ISBN 1-85399-742-0
- Lloyd Llewellyn-Jones and James Robson, Ctesias' History of Persia: Tales of the Orient, Oxford, 2010 (ISBN 9780415364119).