“A man of understanding is to benefit from his enemies...He that knoweth that he hath an enemy will look circumspectly about him to all matters, ordering his life and behaviour in better sort ... therefore it was well and truly said of Antisthenes, that such men as would be saved and become honest ought of necessity to have either good friends or bitter enemies. But forasmuch as amity and friendship nowadays speaketh with a small and low voice, and is very audible and full or words in flattery, what remaineth but that we should hear the truth from the mouth of our enemies? Thine enemy, as thou knowest well enough, watcheth continually, spying and prying into all thine actions. As for our friends, it chanceth many times that they fall extreme sick, yea, and die while we defer and put off from day to day to go and visit them, or make small reckoning of them; but as touch our enemies we are so observant, we curiously inquire even after their very dreams.
The end of all those combats that our forefathers in the old world had against wild beasts was that they might not be wounded or hurt by strange or savage beasts; but those who came after have learned, moreover, how to make use of them; not only take order to keep themselves from receiving any harm or damage by them; but (that which more is) have the skill to draw some commodity from them, feeding of their flesh, clothing their bodies with their wool and hair, curing their maladies with gall and rennet, arming themselves with their hides and skins.”—Plutarch, Moralia qtd. in The Enemy no. 2: A Review of Art and Literature, edited by P. Wyndham Lewis.