Men are disturbed not by the things which happen, but by the opinions about the things: for example, death is nothing terrible, for if it were, it would have seemed so to Socrates; for the opinion about death, that it is terrible, is the terrible thing. When then we are impeded or disturbed or grieved, let us never blame others, but ourselves, that is, our opinions. It is the act of an ill-instructed man to blame others for his own bad condition; it is the act of one who has begun to be instructed, to lay the blame on himself; and of one whose instruction is completed, neither to blame another, nor himself.
Three stages of progress, hidden in the last sentence. The uninstructed blame others. The beginner blames himself. The trained Stoic blames neither — because by then the impression has been caught before sunkatathesis, before assent, and there is nothing to assign blame for.
Epictetus, Enchiridion 5 · trans. George Long (1877)
Context
A short chapter in Epictetus's Enchiridion that articulates the entire Stoic theory of emotion in one sentence. Albert Ellis explicitly cited this passage as the seed of rational-emotive therapy — the event is not the cause of suffering; the judgment about the event is.