Be wary of friends – they will betray you more quickly, for they are easily aroused to envy. They will also become spoiled and tyrannical. But hire a former enemy and he will be more loyal than a friend, because he has more to prove.
greene, robert. The 48 Laws of Power.
The key to power, then, is the ability to judge who is best able to further your interest in all situations. Keep friends for friendships, but work with the skilled and competent.
GREENE, ROBERT. THE 48 LAWS OF POWER.
Without enemies around us, we grow lazy. An enemy at our heels sharpens our wits, keeping us focused and alert. It is sometimes better, then, to use enemies as enemies rather than transforming them into friends or allies.
GREENE, ROBERT. THE 48 LAWS OF POWER.