“If you do not control the enemy, the enemy will control you”

“anger, in and of itself, is a good thing, within reason, but it will be your greatest enemy if you don't learn to control it!”

“Just remember, anger is always your enemy. You must keep your emotions in check. The moment you lose control of them, you lose the fight every time. (Takeshi)”

“The behavior of any bureaucratic organization can best be understood by assuming that it is controlled by a secret cabal of its enemies.”

“The battlefield is a scene of constant chaos. The winner will be the one who controls that chaos, both his own and the enemies”

“An enemy, Ender Wiggin," whispered the old man. "I am your enemy, the first one you've ever had who was smarter than you. There is no teacher but the enemy. No one but the enemy will tell you what the enemy is going to do. No one but the enemy will ever teach you how to destroy and conquer. Only the enemy shows you where you are weak. Only the enemy tells you where he is strong. And the rules of the game are what you can do to him and what you can stop him from doing to you. I am your enemy from now on. From now on I am your teacher.”