To the wise, life is a problem; to the fool, a solution.

What we do now echoes in eternity.

Always follow these two rules: first, act only on what your reasoning mind proposes for the good of humanity, and second, change your opinion if someone shows you it's wrong. This change of mind must proceed only from the conviction that it's both correct and for the common good, but not because it will give you pleasure and make you popular.

All things change, and you yourself are constantly wasting away. So also is the universe.

Think of the country mouse and of the town mouse, and of the alarm and trepidation of the town mouse.

It is the act of a madman to pursue impossibilities .

Live not as though there were a thousand years ahead of you. Fate is at your elbow; make yourself good while life and power are still yours.