Observe your enemies, for they first find out your faults.
We weed out the darnel from the corn and the unfit in war, but do not excuse evil men from the service of the state.
The most necessary learning is that which unlearns evil.
The investigation of the meaning of words is the beginning of education.
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.
As rust corrupts iron, so envy corrupts man.