From you I can learn things that nobody knows.

The essence of training is to allow error without consequence.

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.

Your work is first, learning is first, winning is everything because without it there is nothing.

The only teacher that's worth anything to you is your enemy.

I am especially grateful, however, to have known the fifties, before we began to poison our own civilization - or at least before the effects of the poison began to be felt.