Ταράσσει τοὺς ἀνθρώπους οὐ τὰ πράγματα, ἀλλὰ τὰ περὶ τῶν πραγμάτων δόγματα· οἷον ὁ θάνατος οὐδὲν δεινόν, ἐπεὶ καὶ Σωκράτει ἂν ἐφαίνετο, ἀλλὰ τὸ δόγμα τὸ περὶ τοῦ θανάτου, διότι δεινόν, ἐκεῖνο τὸ δεινόν ἐστιν. ὅταν οὖν ἐμποδιζώμεθα ἢ ταρασσώμεθα ἢ λυπώμεθα, μηδέποτε ἄλλον αἰτιώμεθα, ἀλλ’ ἑαυτούς, τοῦτ’ ἔστι τὰ ἑαυτῶν δόγματα. ἀπαιδεύτου ἔργον τὸ ἄλλοις ἐγκαλεῖν, ἐφ’ οἷς αὐτὸς πράσσει κακῶς· ἠργμένου παιδεύεσθαι τὸ ἑαυτῷ· πεπαιδευμένου τὸ μήτε ἄλλῳ μήτε ἑαυτῷ.
(Epictetus, Ench. 6)
It is not the things themselves that disturb men, but their judgements about these things. For example, death is nothing dreadful, or else Socrates too would have thought so, but the judgement that death is dreadful, this is the dreadful thing. When, therefore, we are hindered, or disturbed, or grieved, let us never blame anyone but ourselves, that means, our own judgements. It is the part of an uneducated person to blame others where he himself fares ill; to blame himself is the part of one whose education has begun; to blame neither another nor his own self is the part of one whose education is already complete. (tr. William Abbott Oldfather)