Any person capable of angering you becomes your master; he can anger you only when you permit yourself to be disturbed by him. - Epictetus

greatness of reason is measured not by height or length, but by the quality of its judgements.

Does anyone bathe in a mighty little time? Don't say that he does it ill, but in a mighty little time. Does anyone drink a great quantity of wine? Don't say that he does ill, but that he drinks a great quantity. For, unless you perfectly understand the principle from which anyone acts, how should you know if he acts ill? Thus you will not run the hazard of assenting to any appearances but such as you fully comprehend. (45).

And every animal is better or worse from his own merit (virtue) or his own badness. Is there then no virtue in man only? and must we look to the hair, and our clothes and to our ancestors?