Of what use is a philosopher who doesn't hurt anybody's feelings?

The art of being a slave is to rule one's master.

As a matter of self-preservation, a man needs good friends or ardent enemies, for the former instruct him and the latter take him to task.

I am not an Athenian or a Greek, but a citizen of the world.

We come into the world alone and we die alone. Why, in life, should we be any less alone?

All things are in common among friends.