All I know is that I do not know anything

Do not grieve over someone who changes all of the sudden. It might be that he has given up acting and returned to his true self.

Are not all things which have opposites generated out of their opposites?

Wisest is he who knows he knows not.

Wars and revolutions and battles are due simply and solely to the body and its desires.

No citizen has any right to be an amateur in the matter of physical training; it is part of his profession as a citizen to keep himself in good condition... [It is] a disgrace for a man to grow old without seeing the beauty and the strength of which his body is capable.

I do nothing but go about persuading you all, old and young alike, not to take thought for your persons or your properties, but and chiefly to care about the greatest improvement of the soul.