Plato, Letters 343b

βέβαιον εἶναι, κωλύειν δʼ οὐδὲν τὰ νῦν στρογγύλα καλούμενα εὐθέα κεκλῆσθαι τά τε εὐθέα δὴ στρογγύλα, καὶ οὐδὲν ἧττον βεβαίως ἕξειν τοῖς μεταθεμένοις καὶ ἐναντίως καλοῦσιν. καὶ μὴν περὶ λόγου γε ὁ αὐτὸς λόγος, εἴπερ ἐξ ὀνομάτων καὶ ῥημάτων σύγκειται, μηδὲν ἱκανῶς βεβαίως εἶναι βέβαιον· μυρίος δὲ λόγος αὖ περὶ ἑκάστου τῶν τεττάρων ὡς ἀσαφές, τὸ δὲ μέγιστον, ὅπερ εἴπομεν ὀλίγον ἔμπροσθεν, ὅτι δυοῖν ὄντοιν, τοῦ τε ὄντος καὶ τοῦ ποιοῦ τινος, οὐ τὸ

nor is there anything to prevent forms which are now called round from being called straight, and the straight round ; and men will find the names no less firmly fixed when they have shifted them and apply them in an opposite sense. Moreover, the same account holds good of the Definition also, that, inasmuch as it is compounded of names and verbs, it is in no case fixed with sufficient firmness. And so with each of the Four, their inaccuracy is an endless topic; but, as we mentioned a moment ago, the main point is this, that while there are two separate things, the real essence and the quality,