Meditations 10.4.1

Εἰ μὲν σφάλλεται, διδάσκειν εὐμενῶς καὶ τὸ παρορώμενον δεικνύναι. εἰ δὲ ἀδυνατεῖς, σεαυτὸν αἰτιᾶσθαι ἢ μηδὲ σεαυτόν.

If someone is mistaken, teach them kindly and show what they have overlooked. If you cannot, blame yourself—or not even yourself.