Plato, Euthyphro, Apology, Crito, Phaedo, Φαίδων 292:

ἀλλὰ μὴν ἐκ τούτων γ’, ἔφη, τῶν ἴσων, ἑτέρων ὄντων ἐκείνου τοῦ ἴσου, ὅμωσ αὐτοῦ τὴν ἐπιστήμην ἐννενόηκάσ τε καὶ εἴληφασ;