“Fear is a powerful enemy, but a useful friend.”

“Nothing is stable in the realm of power, and even closest of friends can be transformed into the worst of enemies.”

“Fear not your enemies, for they can only kill you. Fear not your friends, for they can only betray you. Fear only the indifferent, who permit the killers and betrayers to walk safely on the earth.”

“when you judge the power that is in a person, you must judge their capacities as both friend and as enemy.”

“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.”

“A man has four natural enemies: fear, clarity, power, and old age. Fear, clarity and power can be overcome, but not old age. Its effect can be postponed, but it can never be overcome.”

“Shall there be truth between us, as two men? Not as friends, but as enemies and equals?”

“If the enemy of my enemy is my friend, then surely you should be friend to my friend.”

“why do our enemies shape us more than our friends?”

“It would be foolish to assert that there is no power above mine. Only the attitude that I take toward it will be quite another than that of the religious age: I shall be the enemy of every higher power, while religion teaches us to make it our friend and be humble toward it.”