Euripidis Tragoediae (Nauck 3rd ed.)

The more he insinuated himself little by little into the minds of the citizens, the sharper were the adversaries he obtained—I mean the comic poets, of whom no one attacked him more bitterly or more ingeniously than Aristophanes. Although he showed himself a little-too-unjust judge of Euripidean philosophy and turned many passages of the tragic poet into laughter more for the sake of mockery than out of amusement, nevertheless, with wondrous sharpness and extraordinary subtlety, he subjected the poetry of his adversary to a censorship that was indeed severe, yet not entirely unjust. To the mockery of the comic poets seem to be owed those "partners and helpers," whose labor the poet is reported to have used in composing his plays. In this number, besides Socrates, are mentioned Mnesilochus and Timocrates the Argive, but especially Cephisophon, the poet's slave, who, as in writing tragedies, so too in creating children, provided him aid 21. For this was the license of the comic poets...

...it is clear that he won not with tragedies but with five tetralogies. Suidas: "He took 5 victories, four while living, and one after death, when his nephew Euripides exhibited the drama." [...] Concerning the individual victories of Euripides, [they] cannot be explored by our resources; cf. Bergk in Meineke's Comicorum Graecorum Fragmenta, vol. 2, p. 904.
21) Mnesilochus, the father-in-law of Euripides, is said by Teleclides (see note 15) to "roast" the Euripidean play, and in Aristophanes' Thesmophoriazusae he is festively mocked as a faithful associate of the poet. The Life of Euripides mentions Timocrates the Argive; other witnesses are ignorant of him. But most truly, as I believe, Bergk conjectured that the same man is indicated in the Venetian Scholia to Euripides' Andromache 445, where these things exist: "It is not possible to determine the times of the drama purely; for it has not been performed at Athens; but Callimachus says that Democrates was inscribed on the tragedy." Therefore, by the testimony of Callimachus, Andromache was committed to the stage not at Athens but at Argos, as the play of Democrates or Timocrates. No one is ignorant that poets sometimes issued their plays under another name. Whether that man was called Democrates or Timocrates the Argive is still uncertain. Regarding Cephisophon, cf. the passage of Aristophanes (Comicorum Graecorum Fragmenta 2, p. 1177) brought forward in the Life of Euripides vs. 95. Aristophanes mentions that man in the poet's inventory in the Frogs 1408: "Let him [Euripides] himself sit upon the scales, his children, his wife, and Cephisophon." Dionysus asks in the same place (1452): "Well done, O Palamedes, O wisest nature! Did you find these things yourself, or Cephisophon?" Frogs 944: "Then he reared [the tragedy] with monodies, mixing in Cephisophon." Where the Scholiast says: "Cephisophon was thought to be a slave helping him in poetry, and especially the lyrics, whom they also ridicule as having been with his wife." That Cephisophon had an affair with the wife of Euripides is not probable, even from the silence of Aristophanes. [These stories are] invented [like] those that exist in the Life vs. 90: "He had a house-born youth named Cephisophon; he caught his own wife acting wildly with him. At first, he tried to persuade her not to do wrong; when he could not persuade her, he left the wife to him."