Plato, Letters 345a

τῆς μετοχῆς γενομένης. εἰ μὲν οὖν ἐκ τῆς μιᾶς συνουσίας Διονυσίῳ τοῦτο γέγονεν, τάχʼ ἂν εἴη, γέγονεν δʼ οὖν ὅπως, ἴττω Ζεύς, φησὶν ὁ Θηβαῖος· διεξῆλθον μὲν γὰρ ὡς εἶπόν τε ἐγὼ καὶ ἅπαξ μόνον, ὕστερον δὲ οὐ πώποτε ἔτι. ἐννοεῖν δὴ δεῖ τὸ μετὰ τοῦτο, ὅτῳ μέλει τὸ περὶ αὐτὰ γεγονὸς εὑρεῖν ὅπῃ ποτὲ γέγονεν, τίνι πότʼ αἰτίᾳ τὸ δεύτερον καὶ τὸ τρίτον, πλεονάκις τε οὐ διεξῇμεν· πότερον Διονύσιος ἀκούσας μόνον

Well, then, if such was the effect produced on Dionysius by our one conversation, perhaps it was so; but how this effect was produced God troweth, as the Theban says ; for as I said, I explained my doctrine to him then on one occasion only, and never again since then. And if anyone is concerned to discover how it was that things actually happened as they did in regard to this matter, he ought to consider next the reason why we did not explain our doctrine a second time, or a third time, or still more often. Does Dionysius fancy