Note 9 — Chapter VIII · PLATONIC COMPOSITIONS GENERALLY.
Reading edition
Aristoxenus, Harmon. ii. p. 30. Καθάπερ Ἀριστοτέλης ἀεὶ διηγεῖτο τοὺς πλείστους τῶν ἀκουσάντων παρὰ Πλάτωνος τὴν περὶ τοῦ ἀγαθοῦ ἀκρόασιν παθεῖν· προσεῖναι γὰρ ἕκαστον ὑπολαμβάνοντα λήψεσθαί τι τῶν νομιζομένων ἀνθρωπίνων ἀγαθῶν· — ὅτε δὲ φανείησαν οἱ λόγοι περὶ μαθημάτων καὶ ἀριθμῶν καὶ γεωμετρίας καὶ ἀστρολογίας, καὶ τὸ πέρας ὅτι ἀγαθόν ἐστιν ἕν, παντελῶς οἶμαι παράδοξον ἐφαίνετο αὐτοῖς.
Compare Themistius, Orat. xxi. p. 245 D. Proklus also alludes to this story, and to the fact that most of the πολὺς καὶ παντοῖος ὄχλος, who were attracted to Plato’s ἀκρόασις περὶ Τἀγαθοῦ, were disappointed or unable to understand him, and went away. (Proklus ad Platon. Parmen. p. 92, Cousin. 528, Stallb.)