It is easy enough to be friendly to one's friends. But to befriend the one who regards himself as your enemy is the quintessence of true religion. The other is mere business.
Business Easy Enemy Enough Friendly
The supreme art of war is to subdue the enemy without fighting.
Art Of War Enemy Fighting Subdue Supreme
Thus the expert in battle moves the enemy, and is not moved by him.
It takes quite a spine to turn the other cheek. It takes phenomenal fortitude to love your enemy. It takes firm resolve to pray for those who persecute you. (with reference to Matthew 5)
The chief enemy of creativity is good sense.
The greatest enemy is one that has nothing to lose.