The only true wisdom is in knowing you know nothing.

Envy is the ulcer of the soul.

The beginning of wisdom is a definition of terms.

If I had engaged in politics, O men of Athens, I should have perished long ago, and done no good either to you or to myself.

The friend must be like money, that before you need it, the value is known.

If I tell you that I would be disobeying the god and on that account it is impossible for me to keep quiet, you won't be persuaded by me, taking it that I am ionizing. And if I tell you that it is the greatest good for a human being to have discussions every day about virtue and the other things you hear me talking about, examining myself and others, and that the unexamined life is not livable for a human being, you will be even less persuaded.

Wisdom is knowing what you don't know.