Book 4
2.25
And what do you suppose a man must know to know himself, his own name merely? Or must he consider what sort of a creature he is for human use and get to know his own powers; just as those who buy horses don’t think that they know the beast they want to know until they have considered whether he is docile or stubborn, strong or weak, fast or slow, and generally how he stands in all that makes a useful or a useless horse?That leads me to think that he who does not know his own powers is ignorant of himself.
2.26
Is it not clear too that through self-knowledge men come to much good, and through self-deception to much harm? For those who know themselves, know what things are expedient for themselves and discern their own powers and limitations. And by doing what they understand, they get what they want and prosper: by refraining from attempting what they do not understand, they make no mistakes and avoid failure. And consequently through their power of testing other men too, and through their intercourse with others, they get what is good and shun what is bad.
2.27
Those who do not know and are deceived in their estimate of their own powers, are in the like condition with regard to other men and other human affairs. They know neither what they want, nor what they do, nor those with whom they have intercourse; but mistaken in all these respects, they miss the good and stumble into the bad.
