Diogenes Laertius on Reading and Writing Plato

III.37 (Plato)

And according to Favorinus, when Plato read the dialogue On the Soul, Aristotle alone stayed to the end; the rest of the audience got up and went away. Some say that Philippus of Opus copied out the Laws, which were left upon waxen tablets, and it is said that he was the author of the Epinomis. Euphorion and Panaetius relate that the beginning of the Republic was found several times revised and rewritten, and the Republic itself Aristoxenus declares to have been nearly all of it included in the Controversies of Protagoras.

From http://www.perseus.tufts.edu/hopper/text?doc=Perseus%3Atext%3A1999.01.0258%3Abook%3D3%3Achapter%3D1