Epictetus · The Handbook
Chapter 42
When someone treats you badly or speaks badly of you, remember: he does it or says it thinking it is his duty. He cannot follow what appears right to you – only what appears right to him. So if it appears wrong to him, he is the one harmed, since he is also the one deceived. If someone takes a true conjunction to be false, the conjunction is not harmed – the one deceived is. Start from this, and you will be gentle with the person who insults you. Say, each time: “It seemed so to him.”
ὅταν σέ τις κακῶς ποιῇ ἢ κακῶς λέγῃ, μέμνησο, ὅτι καθήκειν αὐτῷ οἰόμενος ποιεῖ ἢ λέγει. οὐχ οἷόν τε οὖν ἀκολουθεῖν αὐτὸν τῷ σοὶ φαινομένῳ, ἀλλὰ τῷ ἑαυτῷ, ὥστε, εἰ κακῶς αὐτῷ φαίνεται, ἐκεῖνος βλάπτεται, ὅστις καὶ ἐξηπάτηται. καὶ γὰρ τὸ ἀληθὲς συμπεπλεγμένον ἄν τις ὑπολάβῃ ψεῦδος, οὐ τὸ συμπεπλεγμένον βέβλαπται, ἀλλ’ ὁ ἐξαπατηθείς. ἀπὸ τούτων οὖν ὁρμώμενος πρᾴως ἕξεις πρὸς τὸν λοιδοροῦντα. ἐπιφθέγγου γὰρ ἐφ’ ἑκάστῳ ὅτι «ἔδοξεν αὐτῷ.»