Epictetus

It is the act of an ill-instructed man to blame others for his own bad condition; 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.

Epictetus, 50–135
It is the act of an ill-instructed man to blame others for his own bad condition; 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. — Epictetus