Gonzalez Lodge, Commentary on Plato: Gorgias

ἡ ἐν τοῖς ἀγῶσιν: Plato considers as a species of flattery only that kind of cithara-playing which was practised in the musical contests at the public festivals. On the other hand, he recognizes a variety of this music which may be helpful to the proper cultivation of the soul of the individual who practises it, and indeed may elevate his moral feeling. This he himself recommends in Rep. iii. 399 d f. Cithara-playing was a part of the education of all young Athenians.

ἡ τῶν χορῶν διδασκαλία: διδασκαλία denotes the drill of the chorus for orchestral exhibition as well as for singing. It was the business of the poet. Hdt. i. 23 says of Arion ἐόντα κιθαρῳδὸν τῶν τότε ἐόντων οὐδενὸς δεύτερον καὶ διθύραμβον πρῶτον ἀνθρώπων τῶν ἡμεῖς ἴδμεν ποιήσαντά τε καὶ ὀνομάσαντα καὶ διδάξαντα ἐν Κορίνθῳ. What is to be understood here by choruses is explained by the addition ἡ διθυράμβων ποίησις. It is not all choric lyric which is condemned, but only that part of it which from its connexion with the Dionysus cult had found entrance into Athens and had there been much fostered by the state, which entrusted both native and foreign musicians with the arrangement and production of the dithyramb at the Dionysiac festivals, where contests （ἀγῶνες) took place in it. The founder of dithyrambic melic was the just-named Arion of Methymne (B.C. 600), who resided at the court of Periander of Corinth. He was said to have introduced the strophic arrangement, and the so-called cyclic chorus (consisting of fifty members), which was thus named because the chorus was arranged in a circle around the altar. The second period of the dithyramb begins with the settling in Athens of Lasus of Hermione, a contemporary of the Pisistratidae and a teacher of Pindar. But it soon degenerated in Athens by excessive over-refinement and fantastic cultivation, until it received a new impulse towards the end of the Peloponnesian war by the more artistic cultivation of the dramatic and musical elements by Philoxenus of Cythera.

Κινησίας: a very popular dithyrambic poet about the middle of the Peloponnesian war, who deserves a great deal of censure for having helped to debase dithyrambic poetry. He tried to produce a striking effect by fantastic, misty, and often immoral subjects, combined with a pompous diction, excess of imagery, and shallow figures of speech. And he succeeded in a way, for he was ridiculed by the comic poets Strattis (who composed a comedy upon him), Plato Comicus, and also Aristophanes in the Clouds and the Frogs, as a sinner against art and taste,—one of those who are called in Nub. 333 κυκλίων χορῶν ᾀσματοκάμπται. Of his father Meles we know less; he was certainly less important than Cinesias, though he also is ridiculed by the comic poets.