Passage 6.17.8
οὗτος ὁ Γοργίας πατρὸς μὲν ἦν Χαρμαντίδου, λέγεται δὲ ἀνασώσασθαι μελέτην λόγων πρῶτος ἠμελημένην τε ἐς ἅπαν καὶ ἐς λήθην ὀλίγου δεῖν ἥκουσαν ἀνθρώποις· εὐδοκιμῆσαι δὲ Γοργίαν λόγων ἕνεκα ἔν τε πανηγύρει τῇ Ὀλυμπικῇ φασι καὶ ἀφικόμενον κατὰ πρεσβείαν ὁμοῦ Τισίᾳ παρʼ Ἀθηναίους. καίτοι ἄλλα τε Τισίας ἐς λόγους ἐσηνέγκατο καὶ πιθανώτατα τῶν καθʼ αὑτὸν γυναικὶ Συρακουσίᾳ χρημάτων ἔγραψεν ἀμφισβήτησιν·
This Gorgias was the son of Charmantides, and it is said that he was the first to restore to prominence the study of rhetoric, which had been entirely neglected and had nearly passed into oblivion among humanity. They say that Gorgias gained fame for his eloquence both at the Olympic festival and when he came, together with Tisias, on an embassy to Athens. Indeed, Tisias himself made numerous contributions to rhetoric, and among the most persuasive speeches of his time was a judicial argument he composed for a Syracusan woman concerning a dispute over property.