“Be careful how you choose your enemy, for you will come to resemble him. The moment you adapt your enemy's methods your enemy has won. The rest is suffering and historical opera. ”

“Choose your friends carefully but don’t worry about your enemies, they will choose you”

“Hate is your enemy; you must defeat it! Anger is your enemy; you must defeat it! Violence is your enemy; you must defeat it! Death is your enemy; you must defeat it! Know well your real enemies!”

“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 only 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. I will devise the strategy of your army, and you will learn to be quick and discover what tricks the enemy has for you. Remember, boy. From now on the enemy is more clever than you. From now on the enemy is stronger than you. From now on you are always about to lose.”

“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.”

“You must never call your enemy by a name you choose for him." “Instead you must call him by the name he calls himself. What he chooses will reflect his pride; it will reveal his desires. But what you choose to call him will reveal your fears, which should be kept to yourself, lest your enemy find the way to exploit them.”