Page 219 - Enders_Game_Full_Book

"I think you're cheating," Ender told Mazer one day,
"Oh?"
"You can observe my practice sessions. You can see what I'm working on. You seem to be ready for everything I do."
"Most of what you see is computer simulations," Mazer said. "The computer is programmed to respond to your innovations only after you use them once in battle."
"Then the computer is cheating."
"You need to get more sleep, Ender."
But he could not sleep. He lay awake longer and longer each night, and his sleep was less restful. He woke too often in the night. Whether he was waking up to think more about the game or to escape from his dreams, he wasn't sure. It was as if someone rode him in his sleep, forcing him to wander through his worst memories, to live in them again as if they were real. Nights were so real that days began to seem dreamlike to him. He began to worry that he would not think clearly enough, that he would be too tired when he played. Always when the game began, the intensity of it awoke him, but if his mental abilities began to slip, he wondered, would he notice it?
And he seemed to be slipping. He never had a battle anymore in which he did not lose at least a few fighters. Several times the enemy was able to trick him into exposing more weakness than he meant to; other times the enemy was able to wear him down by attrition until his victory was as much a matter of luck as strategy. Mazer would go over the game with a look of contempt on his face. "Look at this," he would say. "You didn't have to do this." And Ender would return to practice with his leaders, trying to keep up their morale, but sometimes letting slip his disappointment with their weaknesses, the fact that they made mistakes.
"Sometimes we make mistakes," Petra whispered to him once. It was a plea for help.
"And sometimes we don't," Ender answered her. If she got help, it would not be from him. He would teach; let her find her friends among the others.
Then came a battle that nearly ended in disaster. Petra led her force too far; they were exposed, and she discovered it in a moment when Ender wasn't with her. In only a few moments she had lost all but two of her ships.
Ender found her then, ordered her to move them in a certain direction; she didn't answer. There was no movement. And in a moment those two fighters, too, would be lost.
Ender knew at once that he had pushed her too hard because of her brilliance -- he had called on her to play far more often and under much more demanding circumstances than