Plato, Letters 318d

μηχανῴμην ὅπως οὗτοι μὴ δώσουσιν δίκην. καὶ ταῦτα μὲν ταύτῃ περὶ τὰ πολιτικὰ κοινωνίας τῆς ἐμῆς καὶ σῆς· καὶ εἴ τινα ἑτέραν ἀλλοτριότητα ἐνεῖδες ἐν ἐμοὶ πρὸς σέ, εἰκότως οἴει ταύτῃ πάντα ταῦτα γεγονέναι. καὶ μὴ θαύμαζε· κακὸς γὰρ ἂν ἔχοντί γε νοῦν ἀνδρὶ φαινοίμην ἐνδίκως, πεισθεὶς ὑπὸ τοῦ μεγέθους τῆς σῆς ἀρχῆς τὸν μὲν παλαιὸν φίλον καὶ ξένον κακῶς πράττοντα διὰ σέ, μηδὲν σοῦ χείρω, ἵνα οὕτως εἴπω,

Such, then, was the course of events as regards our association in political affairs. And if you perceived any other estrangement in my attitude towards you, you may reasonably suppose that that was the way in which all these things took place. Nor need you be surprised; for I should justly be accounted base by any man of sense had I been influenced by the greatness of your power to betray my old and intimate guest-friend—a man, to say the least, in no wise inferior to you—