Tao Te Ching: Chapter 30
He who knows other men is discerning; he who knows himself is intelligent. He who overcomes others is strong; he who overcomes himself is mighty. He who is satisfied with his lot is rich; he who goes on acting with energy has a (firm) will.
He who does not fail in the requirements of his position, continues long; he who dies and yet does not perish, has longevity.