A wise man gets more use from his enemies than a fool from his friends.

It pays to know the enemy - not least because at some time you may have the opportunity to turn him into a friend.

If you have an enemy, then learn and know your enemy, don't just be mad at him or her

You shall judge of a man by his foes as well as by his friends.

Know your enemy, know his sword.

The wise man draws more advantage from his enemies than the fool from his friends.

A man can learn wisdom even from a foe

Love your Enemies, for they tell you your Faults.

The wise learn many things from their enemies.

Know your enemy — and learn about his favorite sport.

Better that right counsels be known to enemies than that the evil secrets of tyrants should be concealed from citizens.

If a man be the enemy of another from mistake and prejudice, as in the case of religious opinions, and sometimes in politics, that man is different to an enemy at heart with a criminal intention; and it is incumbent upon as, and it contributes also to our own tranquillity, that we

A doubtful friend is worse than a certain enemy. Let a man be one thing or the other, and we then know how to meet him.

Before we can master an enemy, we must know its name, its habits, and its place of abode.