"There was no doubt now in Ender's mind. There was no help for him. Whatever he faced, now and forever, no one would save him from it. Peter might be scum, but Peter had been right, always right; the power to cause pain is the only power that matters, the power to kill and destroy, because if you can't kill then you are always subject to those who can, and nothing and no one will ever save you."

Next Quote

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.

— Orson Scott Card