Harry Potter and the Methods of Rationality

used Transfiguration in combat and he was still alive. If the Headmaster thought the second degree was enough, it was enough.

That Harry was certainly going to fail was, of course, completely irrelevant.

The two of them started setting up the wards and detection webs. The most important web was the one that checked to make sure no Transfigured material had entered the air. Harry would be enclosed in a separate shell of force with its own air supply just to be certain, only his wand allowed to leave the shield, and the interface tight. They were inside Hogwarts so they couldn't automatically Apparate out any material that showed signs of spontaneous combustion, but they could launch it out a skylight almost as fast, the windows all folded outward for exactly that reason. Harry himself would go out a different skylight at the first sign of trouble.

Harry watched them working, his face looking a little frightened.

"Don't worry," said Professor McGonagall in the middle of her running description, "this almost certainly won't be necessary, Mr. Potter. If we expected anything to go wrong you would not be allowed to try. It's just ordinary precautions for any Transfiguration no one has ever tried before."

Harry swallowed and nodded.

And a few minutes later, Harry was strapped into the safety chair and resting his wand against a metal ball - one that, based on his current test scores, should have been too large for him to Transfigure in less than thirty minutes.

And a few minutes after that, Minerva was leaning against the wall, feeling faint.

There was a small patch of glass on the ball where Harry's wand had rested.

Harry didn't say I told you so, but the smug look on his sweating face said it for him.

Dumbledore was casting analytic Charms on the ball, looking more and more intrigued by the moment. Thirty years had melted off his face.

"Fascinating," said Dumbledore. "It's exactly as he claimed. He simply Transfigured a part of the subject without Transfiguring the whole. You say it's really just a conceptual limitation, Harry?"

"Yes," Harry said, "but a deep one, just knowing it had to be a conceptual limitation wasn't enough. I had to suppress the part of my mind that was making the error and think instead about the underlying reality that scientists figured out."

"Truly fascinating," Dumbledore said. "I take it that for any other wizard to do the same would require months of study if they could do it at all? And may I ask you to partially Transfigure some other subjects?"

"Probably yes and of course," Harry said.

Half an hour later, Minerva was feeling equally bewildered, but considerably reassured about the safety issues.

It was the same, aside from being logically impossible.

"I believe that's enough, Headmaster," Minerva said finally. "I suspect partial Transfiguration is more tiring than the ordinary sort."

"Getting less so with practice," said the exhausted and pale boy, voice unsteady, "but yeah, you've got that right."

The process of extracting Harry from the wards took another minute, and then Minerva escorted him to a much more comfortable chair, and Dumbledore produced an ice-cream soda.

"Congratulations, Mr. Potter!" said Professor McGonagall, and meant it. She would have bet almost anything against that working.

"Congratulations indeed," said Dumbledore. "Even I did not make any original discoveries in Transfiguration before the age of fourteen. Not since the day of Dorotea Senjak has any genius flowered so early."

"Thanks," Harry said, sounding a little surprised.

"Nonetheless," Dumbledore said thoughtfully, "I think it would be most wise to keep this happy event a secret, at least for now. Harry, did you discuss your idea with any other person before you spoke to Professor McGonagall?"

There was silence.

"Um..." Harry said. "I don't want to turn anyone over to the Inquisition, but I did tell one other student -"

The word almost exploded from Professor McGonagall's lips. "What? You discussed a completely novel form of Transfiguration with a student before consulting a recognized authority? Do you have any idea how irresponsible that was?"

"I'm sorry," said Harry. "I didn't realize."

The boy looked appropriately frightened, and Minerva felt something inside her relax. At least Harry understood how foolish he'd been.

"You must swear Miss Granger to secrecy," Dumbledore said gravely. "And do not tell anyone else unless there is an extremely good reason for it, and they too have sworn."

"Ah... why?" Harry said.

Minerva was wondering the same thing. Once again the Headmaster was thinking too far ahead for her to keep up.

"Because you can do something that no one else will believe you can do," Dumbledore said. "Something completely unexpected. It may prove to be your critical advantage, Harry, and we must preserve it. Please, trust me in this."

Professor McGonagall nodded, her firm face showing nothing of her inner confusion. "Please do, Mr. Potter," she