Plato, Letters 313c

περὶ τὸ φανταζόμενον, τὸ δὲ οὐδέν ἐστιν τοιοῦτον. καὶ τοῦτο οὐ σοὶ μόνῳ γέγονεν, ἀλλʼ εὖ ἴσθι μηδένα πώποτέ μου τὸ πρῶτον ἀκούσαντα ἔχειν ἄλλως πως ἢ οὕτως κατʼ ἀρχάς, καὶ ὁ μὲν πλείω ἔχων πράγματα, ὁ δὲ ἐλάττω, μόγις ἀπαλλάττονται, σχεδὸν δὲ οὐδεὶς ὀλίγα. τούτων δὴ γεγονότων καὶ ἐχόντων οὕτω, σχεδὸν κατὰ τὴν ἐμὴν δόξαν ηὑρήκαμεν ὃ σὺ ἐπέστειλας, ὅπως δεῖ πρὸς ἀλλήλους ἡμᾶς ἔχειν. ἐπεὶ γὰρ βασανίζεις αὐτὰ συγγιγνόμενός τε ἄλλοις καὶ παραθεώμενος

Nor are you alone in this experience; on the contrary, there has never yet been anyone, I assure you, who has not suffered the same confusion at the beginning, when he first learnt this doctrine from me; and they all overcome it with difficulty, one man having more trouble and another less, but scarcely a single one of them escapes with but little. So now that this has occurred, and things are in this state, we have pretty well found an answer, as I think, to the question how we ought to behave towards each other. For seeing that you are testing my doctrines both by attending the lectures of other teachers and