Antisthenes

As iron is eaten away by rust, so the envious are consumed by their own passion.

The most useful piece of learning for the uses of life is to unlearn what is untrue.

I am sadly afraid that I must have done some wicked thing.

Quarrels often arise in marriages when the bridal gifts are excessive.

There are only two people who can tell you the truth about yourself - an enemy who has lost his temper and a friend who loves you dearly.

Observe your enemies, for they first find out your faults.

Pay attention to your enemies, for they are the first to discover your mistakes.