The principle of contradiction establishes merely the agreement of concepts, but does not itself produce concepts.

It is only when a man is alone that he is really free.

How is it possible that suffering that is neither my own nor of my concern should immediately affect me as though it were my own, and with such force that is moves me to action?

If a man wants to read good books, he must make a point of avoiding bad ones; for life is short, and time and energy limited.

It is, indeed, only in old age that intellectual men attain their sublime expression, whilst portraits of them in their youth show only the first traces of it.

Pride works _from within_; it is the direct appreciation of oneself. Vanity is the desire to arrive at this appreciation indirectly, from without.

This world could not have been the work of an all-loving being, but that of a devil, who had brought creatures into existence in order to delight in the sight of their sufferings.