I don't care how much you eat, Ender, self-cannibalism won't get you out of this school.

Any decent person who knows what warfare is can never go into battle with a whole heart.

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.

No human being, when you understand his desires, is worthless. No one's life is nothing. Even the most evil of men and women, if you understand their hearts, had some generous act that redeems them, at least a little, from their sins.

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.

The commercial work of today is the classics of tomorrow.

Don't lie to me! Don't seem so normal when I know you have cut yourself off from me in your heart! If you can put on our affectionate closeness like a mask, then I'll never be able to take joy in it again.