(Θρασύμαχος), a native of Chalcedon. was a siophist, and one of the earliest cultivators of the art of rhetoric. He was a contemporary of Gorgias. (Cic. Orat. 12. 13, 52 ; Quintil. iii. 50.10.) He is introduced by Plato as one of the interlocutors in the Politeia, and is referred to several times in the Phaedrus. Like Prodicus and Protagoras, he discoursed and wrote on subjects of natural philosophy (Cic. de Orat. 3.32.128) : Plutarch (Symp. p. 616d.) mentions a work by him on Illustrious Men (Τ̔περβάλλοντες). Quintilian speaks of him as one of the rinst who wrote on common places (Probably in the ἀφορμαὶ ῥητορικαι mentioned by Suid. s. v. Θρας.) He seems to have been particularly fond of making his syllables fill into vaeons (Quint. Inst. 9.4.87). Suidas, who very stupidly makes him a disciple of Plato and Isocrates, mentions as his works -1. Orations (σνμβουλευτικοί). 2. Τέχνη ρ́ητορική. 3.Παίγνια. 4. Ἀφορμαὶ ῥητορικαί. Athenaeus (x. p. 416) quotes from one of his introductions. The following epitaph was placed upon his monument at Chalcedon : τοὔνομα Θήτα, ρῶ, ἄλφα, σάν, ὖ, μῦ, ἂλφα, χῖ, οὖ, σάν.Πατρὶς Χαλκηδών ἡ δὲ τέχνη σοφίη.

(Athen. 10.454.)