Eliezer Yudkowsky - Harry Potter and the Methods of Rationality

Professor Quirrell took a sip of his water. "But I digress. The new evidence that the Headmaster promises to provide is to exhibit a previously undetected spell on the Sorting Hat, which, the Headmaster asserts, he has personally determined to respond only to Slytherins who are also Parselmouths. The Headmaster further argues that this favors the interpretation that the Chamber of Secrets was indeed opened in 1943, approximately the right time frame for He-Who-Must-Not-Be-Named, a known Parselmouth, to have attended Hogwarts. It is a rather questionable logic, but a judicial panel may rule that it swings the case far enough to bring Mr. Hagrid's guilt into doubt, if they can manage to keep a straight face as they say it. And now we come to the key question: how did the Headmaster discover this hidden spell on the Sorting Hat?"

Professor Quirrell was smiling thinly now. "Well now, let us suppose that there was a Parselmouth in this year's crop of students, a potential Heir of Slytherin. You must admit, Mr. Potter, that you stand out as a possibility whenever extraordinary people are considered. And if I then further ask myself which new Slytherin would be most likely to have his mental privacy invaded by the Headmaster, specifically hunting the memories of his Sorting, why, you stand out even more." The smile vanished. "So you see, Mr. Potter, it was not I who invaded your mind, though I will not ask you to apologize. It is not your fault that you believed Dumbledore's protestations of respecting your mental privacy."

"My sincere apologies," Harry said, keeping his face expressionless. The rigid control was a confession in its own right, as was the sweat beading his forehead; but he didn't think the Defense Professor would take any evidence from that. Professor Quirrell would just think Harry was nervous at having been discovered as the Heir of Slytherin. Rather than being nervous that Professor Quirrell might realize that Harry had deliberately betrayed Slytherin's secret... which itself was no longer seeming like such a smart move.

"So, Mr. Potter. Any progress on finding the Chamber of Secrets?"

No, thought Harry. But to maintain plausible deniability, you needed a general policy of sometimes evading questions even when you had nothing to hide... "With respect, Professor Quirrell, if I had made such progress, it is not quite obvious to me that I should tell you about it."

Professor Quirrell sipped from his own waterglass again. "Well then, Mr. Potter, I shall freely tell you what I know or suspect. First, I believe the Chamber of Secrets is real, as is Slytherin's Monster. Miss Myrtle's death was not discovered until hours after her demise, even though the wards should have alerted the Headmaster instantly. Therefore her murder was performed either by Headmaster Dippet, which is unlikely, or by some entity which Salazar Slytherin keyed into his wards at a higher level than the Headmaster himself. Second, I suspect that contrary to popular legend, the purpose of Slytherin's Monster was not to rid Hogwarts of Muggleborns. Unless Slytherin's Monster were powerful enough to defeat the Headmaster of Hogwarts and all the teachers, it could not triumph by force. Multiple murders in secrecy would result in the school's closure, as nearly happened in 1943, or in the placing of new wards. So why Slytherin's Monster, Mr. Potter? What true purpose does it serve?"

"Ah..." Harry dropped his gaze to his waterglass and tried to think. "To kill anyone who got into the Chamber and didn't belong there -"

"A monster powerful enough to defeat a team of wizards that had broken past the best wards Salazar could place on his Chamber? Unlikely."

Harry was feeling a bit pressured now. "Well, it's called the Chamber of Secrets, so maybe the Monster has a secret, or is a secret?" For that matter, just what sort of secrets were in the Chamber of Secrets in the first place? Harry hadn't done a lot of research on the subject, in part because he'd gotten the impression that nobody knew anything -

Professor Quirrell was smiling. "Why not just write the secret down?"

"Ahhh..." said Harry. "Because if the Monster spoke Parseltongue, that would ensure that only a true descendant of Slytherin could hear the secret?"

"Easy enough to key the wards on the Chamber to a phrase spoken in Parseltongue. Why go to the trouble of creating Slytherin's Monster? It cannot have been easy to create a creature with a lifespan of centuries. Come, Mr. Potter, it should be obvious; what are the secrets that can be told from one living mind to another, but never written down?"

Harry saw it then, with a burst of adrenaline that started his heart racing, his breath coming faster. " Oh. "

Salazar Slytherin had been very cunning indeed. Cunning enough to come up with a way to bypass the Interdict of Merlin.

Powerful wizardries couldn't be transmitted through books or ghosts, but if you could create a long-lived enough sentient creature with a good enough memory -

"It seems very probable to me," said Professor Quirrell, "that He-Who-Must-Not-Be-Named began his climb to power with secrets obtained from Slytherin's Monster. That Salazar's lost knowledge is the source of You-Know-Who's extraordinarily powerful wizardry. Hence my interest in the Chamber of Secrets and the case of Mr. Hagrid."

"I see ," Harry said. And if he, Harry, could find Salazar's Chamber of Secrets... then all of the lost knowledge that Lord Voldemort had obtained would be his as well.

Yes. That was just how the story should go.

Add in Harry's superior intelligence and some original magical research and some Muggle rocket launchers, and the resulting fight would be completely one-sided, which was exactly how Harry wanted it.

Harry was grinning now, a very evil grin. New priority: Find everything in Hogwarts that looks remotely like a snake and try speaking to it. Starting with everything you've already tried, only this time be sure to use Parseltongue instead of English - get Draco to let you into the Slytherin dorms -

"Don't become too excited, Mr. Potter," said Professor Quirrell. His own face had become expressionless, now. "You must continue thinking. What were the Dark Lord's parting words to Slytherin's Monster?"

" What? " Harry said. "How could either of us possibly know that?"

"Visualize the scene, Mr. Potter. Let your imagination fill in the details. Slytherin's Monster - probably some great serpent, so that only a Parselmouth may speak to it - has finished imparting all of the knowledge it possesses to He-Who-Must-Not-Be-Named. It conveys to him Salazar's final benediction, and warns him that the Chamber of Secrets must now remain closed until the next descendant of Salazar should prove cunning enough to open it. And he who will become the Dark Lord nods, and says to it -"

"Avada Kedavra," said Harry, suddenly feeling sick to his stomach.

"Rule Twelve," Professor Quirrell said quietly. "Never leave the source of your power lying around where someone else can find it."

Harry's gaze dropped to the tablecloth, which had decorated itself in a mournful pattern of black flowers and shadows. Somehow that seemed... too sad to be imagined, Slytherin's great snake had only wanted to help Lord Voldemort, and Lord Voldemort had just... there was something unbearably sorrowful about it, what sort of person would do that to a being who'd offered them nothing but friendship... " Do you think the Dark Lord would have -"

"Yes," Professor Quirrell said flatly. "He-Who-Must-Not-Be-Named left quite a trail of bodies behind him, Mr. Potter; I doubt he would have omitted that one. If there were any artifacts left there that could be moved, the Dark Lord would have taken those with him as well. There might still be something worth seeing in the Chamber of Secrets, and to find it would prove yourself the true Heir of Slytherin. But do not raise your hopes too high. I suspect that all you will find is the remains of Slytherin's Monster resting quietly in its grave."