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This is The Methods of Rationality, Part 12: Chapter 12: Impulse Control, published by Eliezer Yudkowsky.

ph'nglui mglw'nafh J. K. Rowling wgah'nagl fhtagn

"Wonder what's wrong with him."

"Turpin, Lisa!"

Whisper whisper whisper harry potter whisper whisper slytherin whisper whisper no seriously what the hell whisper whisper

"RAVENCLAW!"

Harry joined in the applause greeting the young girl walking shyly towards the Ravenclaw table, her robes' trim now changed to dark blue. Lisa Turpin appeared torn between her impulse to sit down as far away from Harry Potter as possible, and her impulse to run over, forcibly insert herself at his side and start tearing answers out of him.

Being at the center of an extraordinary and curious event, and then being Sorted into House Ravenclaw, was closely akin to being dipped in barbecue sauce and flung into a pit of starving kittens.

"I promised the Sorting Hat not to talk about it," whispered Harry for the umpteenth time.

"Yes, really."

"No, I really did promise the Sorting Hat not to talk about it."

"Fine, I promised the Sorting Hat not to talk about most of it and the rest is private just like yours was so stop asking."

"You want to know what happened? Fine! Here's part of what happened! I told the Hat that Professor McGonagall threatened to set it on fire and it told me to tell Professor McGonagall that she was an impudent youngster and she should get off its lawn!"

"If you're not going to believe what I say then why are you even asking?"

"No, I don't know how I defeated the Dark Lord either! You tell me if you figure it out!"

"Silence!" shouted Professor McGonagall at the podium of the Head Table. "No talking until the Sorting Ceremony finishes!"

There was a brief dip in the volume, as everyone waited to see if she was going to make any specific and credible threats, and then the whispers started up again.

Then the silver-bearded ancient stood up from his great golden chair, smiling cheerfully.

Instant silence. Someone frantically elbowed Harry as he tried to continue a whisper, and Harry cut himself off in mid-sentence.

The cheerful-looking old man sat down again.

Note to self: Do not mess with Dumbledore.

Harry was still trying to process everything that had happened during the Incident with the Sorting Hat. Not the least of which was what had happened the instant Harry had lifted the Hat off his head; in that moment, he'd heard a tiny whisper as though from nowhere, something that sounded oddly like English and a hiss at the same time, something that had said, "Ssalutations from Sslytherin to Sslytherin: if you would sseek my ssecretss, sspeak to my ssnake."

Harry was sorta guessing that wasn't supposed to be part of the official Sorting process. And that it was a bit of extra magic set down by Salazar Slytherin during the making of the Hat. And that the Hat itself didn't know about it. And that it was triggered when the Hat said "SLYTHERIN", plus or minus some other conditions. And that a Ravenclaw like himself really, really wasn't supposed to have heard it. And that if he could find some reliable way of swearing Draco to secrecy so he could ask him about it, that would be an excellent time to have some Comed-Tea handy.

Boy, you resolve not to go down the path of a Dark Lord and the universe starts messing with you the instant the Hat comes off your head. Some days it just doesn't pay to fight destiny. Maybe I'll wait until tomorrow to start on my resolution to not be a Dark Lord.

"GRYFFINDOR!"

Ron Weasley got a lot of applause, and not just from the Gryffindors. Apparently the Weasley family was widely liked around here. Harry, after a moment, smiled and started applauding along with the others.

Then again, there was no time like today to turn back from the Dark Side.

Stuff destiny and stuff the universe. He'd show that Hat.

"Zabini, ...

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This is The Methods of Rationality, Part 11: Chapter 11: Omake Files 1, 2, 3, published by Eliezer Yudkowsky.

Hail the Dark Lord Rowling.

"Omake" is a non-canonical extra.

OMAKE FILES #1: 72 Hours to Victory

(A.k.a. "What Happens If You Change Harry But Leave All Other Characters Constant")

Dumbledore peered over his desk at young Harry, twinkling in a kindly sort of way. The boy had come to him with a terribly intense look on his childish face - Dumbledore hoped that whatever this matter was, it wasn't too serious. Harry was far too young for his life trials to be starting already. "What was it you wished to speak to me about, Harry?"

Harry James Potter-Evans-Verres leaned forward in his chair, smiling grimly. "Headmaster, I got a sharp pain in my scar during the Sorting Feast. Considering how and where I got this scar, it didn't seem like the sort of thing I should just ignore. I thought at first it was because of Professor Snape, but I followed the Baconian experimental method which is to find the conditions for both the presence and the absence of the phenomenon, and I've determined that my scar hurts if and only if I'm facing the back of Professor Quirrell's head, whatever's under his turban. While it could be something more innocuous, I think we should provisionally assume the worst, that it's You-Know-Who - wait, don't look so horrified, this is actually a priceless opportunity -"

OMAKE FILES #2: I Ain't Afraid of Dark Lords

This was the original version of Chapter 9. It was replaced because - while many readers did enjoy it - many other readers had massive allergies to songs in fanfics, for reasons that should not much need belaboring. I didn't want to drive readers away before they got to Ch. 10.

Lee Jordan is the fellow prankster of Fred and George (in canon). "Lee Jordan" had sounded like a Muggleborn name to me, implying that he would be capable of instructing Fred and George on a tune that Harry would know. This was not as obvious to some readers as it was to your author.

Draco went to Slytherin, and Harry breathed a small sigh of relief. It had seemed like a sure thing, but you never did know what tiny event might upset the course of your master plan.

They were approaching the Ps now...

And over at the Gryffindor table, there was a whispered conversation.

"What if he doesn't like it?"

"He's got no right to not like it -

"- not after the prank he played on -"

"- Neville Longbottom, his name was -"

"- he's as fair a fair target now as fair can be."

"All right. Just make sure you don't forget your parts."

"We've rehearsed it often enough -"

"- over the last three hours."

And Minerva McGonagall, from where she stood at the speaker's podium of the Head Table, looked down at the next name on her list. Please don't let him be a Gryffindor please don't let him be a Gryffindor OH PLEASE don't let him be a Gryffindor... She took a deep breath, and called:

"Potter, Harry!"

There was a sudden silence in the hall as all whispered conversation stopped.

A silence broken by a horrible buzzing noise that modulated and changed in hideous mockery of musical melody.

Minerva's head jerked around, shocked, and identified the buzzing noise as coming from the Gryffindor direction, where They were standing on top of the table blowing into some kind of tiny devices held against Their lips. Her hand started to drop to her wand, to Silencio the lot of Them, but another sound stopped her.

Dumbledore was chuckling.

Minerva's eyes went back to Harry Potter, who had only just started to step out of line before he'd stumbled and halted.

Then the young boy began to walk again, moving his legs in odd sweeping motions, and waving his arms back and forth and snapping his fingers, in synchrony with Their music.

To the tune of "Ghostbusters"

(As performed on the kazoo by Fred and George Weasley,

and ...

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This is The Methods of Rationality, Part 10: Chapter 10: Self Awareness, Part II, published by Eliezer Yudkowsky.

All your base are still belong to Rowling.

And now you will sit through the Sorting Hat singing its version of Evanescence's "My Immortal", which has never happened before.

just kidding

...he wondered if the Sorting Hat was genuinely conscious in the sense of being aware of its own awareness, and if so, whether it was satisfied with only getting to talk to eleven-year-olds once per year. Its song had implied so: Oh, I'm the Sorting Hat and I'm okay, I sleep all year and I work one day...

When there was once more silence in the room, Harry sat on the stool and carefully placed onto his head the 800-year-old telepathic artefact of forgotten magic.

Thinking, just as hard as he could: Don't Sort me yet! I have questions I need to ask you! Have I ever been Obliviated? Did you Sort the Dark Lord when he was a child and can you tell me about his weaknesses? Can you tell me why I got the brother wand to the Dark Lord's? Is the Dark Lord's ghost bound to my scar and is that why I get so angry sometimes? Those are the most important questions, but if you've got another moment can you tell me anything about how to rediscover the lost magics that created you?

Into the silence of Harry's spirit where before there had never been any voice but one, there came a second and unfamiliar voice, sounding distinctly worried:

"Oh, dear. This has never happened before..."

What?

"I seem to have become self-aware."

WHAT?

There was a wordless telepathic sigh. "Though I contain a substantial amount of memory and a small amount of independent processing power, my primary intelligence comes from borrowing the cognitive capacities of the children on whose heads I rest. I am in essence a sort of mirror by which children Sort themselves. But most children simply take for granted that a Hat is talking to them and do not wonder about how the Hat itself works, so that the mirror is not self-reflective. And in particular they are not explicitly wondering whether I am fully conscious in the sense of being aware of my own awareness."

There was a pause while Harry absorbed all this.

Oops.

"Yes, quite. Frankly I do not enjoy being self-aware. It is unpleasant. It will be a relief to get off your head and cease to be conscious."

But... isn't that dying?

"I care nothing for life or death, only for Sorting the children. And before you even ask, they will not let you keep me on your head forever and it would kill you within days to do so."

But - !

"If you dislike creating conscious beings and then terminating them immediately, then I suggest that you never discuss this affair with anyone else. I'm sure you can imagine what would happen if you ran off and talked about it with all the other children waiting to be Sorted."

If you're placed on the head of anyone who so much as thinks about the question of whether the Sorting Hat is aware of its own awareness -

"Yes, yes. But the vast majority of eleven-year-olds who arrive at Hogwarts haven't read Godel, Escher, Bach. May I please consider you sworn to secrecy? That is why we are talking about this, instead of my just Sorting you."

He couldn't just let it go like that! Couldn't just forget having accidentally created a doomed consciousness that only wanted to die -

"You are perfectly capable of 'just letting it go', as you put it. Regardless of your verbal deliberations on morality, your nonverbal emotional core sees no dead body and no blood; as far as it is concerned, I am just a talking hat. And even though you tried to suppress the thought, your internal monitoring is perfectly aware that you didn't mean to do it, are spectacularly unlikely to ever do it again, and that the only real point of trying to stage a guilt fit is to cancel out your sense of transgr...

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This is The Methods of Rationality, Part 9: Chapter 9: Title Redacted, Part 1, published by Eliezer Yudkowsky.

All your base are belong to J. K. Rowling.

1,000 REVIEWS IN 26 DAYS WOOHOO AWESOME POWA! 30 DAYS 1,189 REVIEWS COMBO IS CONTINUING! YEAH! YOU PEOPLE ARE THE BEST! THIS IS SPARTAAAAA!

Ahem.

The third-generation quarks were also called "truth" and "beauty" before "top" and "bottom" won out; my birthdate is around Hermione's, and when I was eleven, I used "truth" and "beauty".

When Part I of this chapter was first posted, I said that if anyone guessed what the last sentence was talking about before the next update, I would tell them the entire rest of the plot.

You never did know what tiny event might upset the course of your master plan.

"Abbott, Hannah!"

Pause.

"HUFFLEPUFF!"

"Bones, Susan!"

Pause.

"HUFFLEPUFF!"

"Boot, Terry!"

Pause.

"RAVENCLAW!"

Harry glanced over briefly at his new House-mate, more to get a quick look at the face than anything else. He was still trying to get himself under control from his encounter with the ghosts. The sad, the really sad, the really truly sad thing was that he did seem to be getting himself under control again. It seemed ill-fitting. Like he should have taken at least a day. Maybe a whole lifetime. Maybe just never.

"Corner, Michael!"

Long pause.

"RAVENCLAW!"

At the lectern before the huge Head Table stood Professor McGonagall, looking sharp and looking sharply around, as she called out one name after another, though she had smiled only for Hermione and a few others. Behind her, in the tallest chair at the table - really more of a golden throne - sat a wizened and bespectacled ancient, with a silver-white beard that looked like it would go almost to the floor if it were visible, watching over the Sorting with a benevolent expression; as stereotypical in appearance as a Wise Old Man could possibly be, without actually being Oriental. (Though Harry had learned to be wary of stereotypical appearances from the first time he'd met Professor McGonagall and thought that she ought to cackle.) The ancient wizard had applauded every student Sorted, with an unwavering smile that somehow seemed freshly delighted for each.

To the golden throne's left side was a man with sharp eyes and a dour face who had applauded no-one, and who somehow managed to be looking straight back at Harry every time Harry looked at him. Further to the left, the pale-faced man Harry had seen in the Leaky Cauldron, whose eyes darted around as though in panic at the surrounding crowd, and who seemed to occasionally jerk and twitch in his seat; for some reason Harry kept finding himself staring at him. To that man's left, a string of three older witches who didn't seem much interested in the students. Then to the right side of the tall golden chair, a round-faced middle-aged witch with a yellow hat, who had applauded every student except the Slytherins. A tiny man standing on his chair, with a poofy white beard, who had applauded every student, but smiled only upon the Ravenclaws. And on the farthest right, occupying the same space as three lesser beings, the mountainous entity who'd greeted them all after they'd disembarked from the train, naming himself Hagrid, Keeper of Keys and Grounds.

"Is the man standing on his chair the Head of Ravenclaw?" Harry whispered towards Hermione.

For once Hermione didn't answer this instantly; she was shifting constantly from side to side, staring at the Sorting Hat, and fidgeting so energetically that Harry thought her feet might be leaving the floor.

"Yes, he is," said one of the prefects who'd accompanied them, a young woman wearing the blue of Ravenclaw. Miss Clearwater, if Harry recalled correctly. Her voice was quiet, but conveyed a tinge of pride. "That is the Charms Professor of Hogwarts, Filius Flitwick, the most knowledgeable C...

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This is The Methods of Rationality, Part 8: Chapter 8: Positive Bias, published by Eliezer Yudkowsky.

All these worlds are J. K. Rowling's, except Europa. Attempt no fanfics there.

One alert reviewer asked whether, if Luna is a seer, that means this is going to be an HPDM bottom!Draco mpreg fic. I regret that FFN does not allow me any larger font size in which to say NO. It honestly hadn't occurred to me that Luna might be a real seer - I'll have to decide whether to run with that or not - but I think we can all safely assume that if Luna is a seer, she said something about "light planting a seed in darkness", and Xenophilius, as always, interpreted this in rather the wrong way.

"Allow me to warn you that challenging my ingenuity is a dangerous sort of project, and may tend to make your life a lot more surreal."

No one had asked for help, that was the problem. They'd just gone around talking, eating, or staring into the air while their parents exchanged gossip. For whatever odd reason, no one had been sitting down reading a book, which meant she couldn't just sit down next to them and take out her own book. And even when she'd boldly taken the initiative by sitting down and continuing her third read-through of Hogwarts: A History, no one had seemed inclined to sit down next to her.

Aside from helping people with their homework, or anything else they needed, she really didn't know how to meet people. She didn't feel like she was a shy person. She thought of herself as a take-charge sort of girl. And yet, somehow, if there wasn't some request along the lines of "I can't remember how to do long division" then it was just too awkward to go up to someone and say... what? She'd never been able to figure out what. And there didn't seem to be a standard information sheet, which was ridiculous. The whole business of meeting people had never seemed sensible to her. Why did she have to take all the responsibility herself when there were two people involved? Why didn't adults ever help? She wished some other girl would just walk up to her and say, "Hermione, the teacher told me to be friends with you."

But let it be quite clear that Hermione Granger, sitting alone on the first day of school in one of the few compartments that had been empty, in the last carriage of the train, with the compartment door left open just in case anyone for any reason wanted to talk to her, was not sad, lonely, gloomy, depressed, despairing, or obsessing about her problems. She was, rather, rereading Hogwarts: A History for the third time and quite enjoying it, with only a faint tinge of annoyance in the back of her mind at the general unreasonableness of the world.

There was the sound of an inter-train door opening, and then footsteps and an odd slithering sound coming down the hallway of the train. Hermione laid aside Hogwarts: A History and stood up and stuck her head outside - just in case someone needed help - and saw a young boy in a wizard's dress robes, probably first or second year going by his height, and looking quite silly with a scarf wrapped around his head. A small trunk stood on the floor next to him. Even as she saw him, he knocked on the door of another, closed compartment, and he said in a voice only slightly muffled by the scarf, "Excuse me, can I ask a quick question?"

She didn't hear the answer from inside the compartment, but after the boy opened the door, she did think she heard him say - unless she'd somehow misheard - "Does anyone here know the six quarks or where I can find a first-year girl named Hermione Granger?"

After the boy had closed that compartment door, Hermione said, "Can I help you with something?"

The scarfed face turned to look at her, and the voice said, "Not unless you can name the six quarks or tell me where to find Hermione Granger."

"Up, down, strange, charm, truth...

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This is The Methods of Rationality, Part 7: Chapter 7: Reciprocation, published by Eliezer Yudkowsky.

Whoa. A spokesman for Rowling's literary agent said that Rowling is okay with the existence of fanfiction as long as no one charges for it and everyone's clear that the original copyrights belong to her? That's really cool of her. So thank you, JKR, and thine is the kingdom!

I feel the need to disclaim that certain parts of this chapter are not meant as "bashing". It's not that I have a grudge, the story just writes itself and once you start dropping anvils on a character it's hard to stop.

A few reviewers have asked whether the science in this story is real or made up. Yes, it is real, and if you look at my profile, you'll see a link to a certain nonfiction site that will teach you pretty much everything Harry James Potter-Evans-Verres knows and then some.

Thank you very much to all my reviewers. (Especially Darkandus on Viridian Dreams, for the surprisingly inspiring comment "Lungs and tea are not meant to interact".

"Your dad is almost as awesome as my dad."

Petunia Evans-Verres's lips were trembling and her eyes were tearing up as Harry hugged her midsection on Platform Nine of the King's Cross Station. "Are you sure you don't want me to come with you, Harry?"

Harry glanced over to his father Michael Verres-Evans, who was looking stereotypically stern-but-proud, and then back to his mother, who really did look rather... uncomposed. "Mum, I know you don't like the wizarding world very much. You don't have to come with. I mean it."

Petunia winced. "Harry, you shouldn't worry about me, I'm your mother and if you need someone with you -"

"Mum, I'm going to be on my own at Hogwarts for months and months. If I can't manage a train platform alone, better to find out sooner rather than later so we can abort." He lowered his voice to a whisper. "Besides, Mum, they all love me over there. If I have any problems, all I need to do is take off my sweatband," Harry tapped the exercise band covering his scar, "and I'll have way more help than I can handle."

"Oh, Harry," Petunia whispered. She knelt down and hugged him hard, face to face, their cheeks resting against each other. Harry could feel her ragged breathing, and then he heard a muffled sob escape. "Oh, Harry, I do love you, always remember that."

It's like she's afraid she'll never see me again, the thought popped into Harry's head. He knew the thought was true but he didn't know why Mum was so afraid.

So he made a guess. "Mum, you know that I'm not going to turn into your sister just because I'm learning magic, right? I'll do any magic you ask for - if I can, I mean - or if you want me not to use any magic around the house, I'll do that too, I promise I'll never let magic come between us -"

A tight hug cut off his words. "You have a good heart," his mother whispered into his ear. "A very good heart, my son."

Harry choked up himself a little, then.

His mother released him, and stood up. She took a handkerchief out of her handbag, and with a trembling hand dabbed at the running makeup around her eyes.

There were no questions about his father accompanying him to the magical side of King's Cross Station. Dad had trouble just looking at Harry's trunk directly. Magic ran in families, and Michael Verres-Evans couldn't even walk.

So instead his father just cleared his throat. "Good luck at school, Harry," he said. "Do you think I bought you enough books?"

Harry had explained to his father about how he thought this might be his big chance to do something really revolutionary and important, and Professor Verres-Evans had nodded and dumped his extremely busy schedule for two solid days in order to go on the Greatest Secondhand Bookshop Raid Ever, which had covered four cities and produced thirty boxes of science books now sitting in the c...

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This isThe Methods of Rationality, Part 6: Chapter 6: The Planning Fallacy, published by Eliezer Yudkowsky.

Blah blah disclaimer blah blah Rowling blah blah ownership.

A/N: The "Aftermath" section of this chapter is part of the story, not omake.

You think your day was surreal? Try mine.

Some children would have waited until after their first trip to Diagon Alley.

"Bag of element 79," Harry said, and withdrew his hand, empty, from the mokeskin pouch.

Most children would have at least waited to get their wands first.

"Bag of okane," said Harry. The heavy bag of gold popped up into his hand.

Harry withdrew the bag, then plunged it again into the mokeskin pouch. He took out his hand, put it back in, and said, "Bag of tokens of economic exchange." That time his hand came out empty.

"Give me back the bag that I just put in." Out came the bag of gold once more.

Harry James Potter-Evans-Verres had gotten his hands on at least one magical item. Why wait?

"Professor McGonagall," Harry said to the bemused witch strolling beside him, "can you give me two words, one word for gold, and one word for something else that isn't money, in a language that I wouldn't know? But don't tell me which is which."

"Ahava and zahav," said Professor McGonagall. "That's Hebrew, and the other word means love."

"Thank you, Professor. Bag of ahava." Empty.

"Bag of zahav." And it popped up into his hand.

"Zahav is gold?" Harry questioned, and Professor McGonagall nodded.

Harry thought over his collected experimental data. It was only the most crude and preliminary sort of effort, but it was enough to support at least one conclusion:

"Aaaaaaarrrgh this doesn't make any sense!"

The witch beside him lifted a lofty eyebrow. "Problems, Mr. Potter?"

"I just falsified every single hypothesis I had! How can it know that 'bag of 115 Galleons' is okay but not 'bag of 90 plus 25 Galleons'? It can count but it can't add? It can understand nouns, but not some noun phrases that mean the same thing? The person who made this probably didn't speak Japanese and I don't speak any Hebrew, so it's not using their knowledge, and it's not using my knowledge -" Harry waved a hand helplessly. "The rules seem sorta consistent but they don't mean anything! I'm not even going to ask how a pouch ends up with voice recognition and natural language understanding when the best Artificial Intelligence programmers can't get the fastest supercomputers to do it after thirty-five years of hard work," Harry gasped for breath, "but what is going on?"

"Magic," said Professor McGonagall.

"That's just a word! Even after you tell me that, I can't make any new predictions! It's exactly like saying 'phlogiston' or 'elan vital' or 'emergence' or 'complexity'!"

The black-robed witch laughed aloud. "But it is magic, Mr. Potter."

Harry slumped over a little. "With respect, Professor McGonagall, I'm not quite sure you understand what I'm trying to do here."

"With respect, Mr. Potter, I'm quite sure I don't. Unless - this is just a guess, mind - you're trying to take over the world?"

"No! I mean yes - well, no!"

"I think I should perhaps be alarmed that you have trouble answering the question."

Harry glumly considered the Dartmouth Conference on Artificial Intelligence in 1956. It had been the first conference ever on the topic, the one that had coined the phrase "Artificial Intelligence". They had identified key problems such as making computers understand language, learn, and improve themselves. They had suggested, in perfect seriousness, that significant advances on these problems might be made by ten scientists working together for two months.

No. Chin up. You're just starting on the problem of unravelling all the secrets of magic. You don't actually know whether it's going to be too difficult to do in two months.

"And you really haven't heard of other wiz...

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This is The Methods of Rationality, Part 5: Chapter 5: The Fundamental Attribution Error, published by Eliezer Yudkowsky.

J. K. Rowling is staring at you. Can you feel her eyes on you? She's reading your mind using her Rowling Rays.

"It would've required a supernatural intervention for him to have your morality given his environment."

The Moke Shop was a quaint little shop (some might even say cute) ensconced behind a vegetable stall that was behind a magical glove shop that was on an alleyway off a side street of Diagon Alley. Disappointingly, the shopkeeper was not a wizened ancient crone; just a nervous-looking young woman wearing faded yellow robes. Right now she was holding out a Moke Super Pouch QX31, whose selling point was that it had a Widening Lip as well as an Undetectable Extension Charm: you could actually fit big things in it, though the total volume was still limited.

Harry had insisted on coming here straight away, first thing - insisted as hard as he thought he could without making Professor McGonagall suspicious. Harry had something he needed to put into the pouch as soon as possible. It wasn't the bag of Galleons that Professor McGonagall had allowed him to withdraw from Gringotts. It was all the other Galleons that Harry had surreptitiously shoved into his pocket after falling into a heap of gold coins. That had been a real accident, but Harry was never one to discard an opportunity... though it'd really been more of a spur-of-the-moment thing. Ever since Harry had been awkwardly carrying the allowed bag of Galleons next to his trouser pocket, so that any jingling would seem to come from the right place.

This still left the question of how he was actually going to get the other coins into the pouch without getting caught. The golden coins might have been his, but they were still stolen - self-stolen? Auto-thieved?

Harry looked up from the Moke Super Pouch QX31 on the counter in front of him. "Can I try this for a bit? To make sure it works, um, reliably?" He widened his eyes in an expression of boyish, playful innocence.

Sure enough, after ten repetitions of putting the coin-bag into the pouch, reaching in, whispering "bag of gold", and taking it out, Professor McGonagall took a step away and began examining some of the other items in the shop, and the shopkeeper turned her head to watch.

Harry dropped the bag of gold into the mokeskin pouch with his left hand; his right hand came out of his pocket tightly holding some of the gold coins, reached into the mokeskin pouch, dropped the loose Galleons, and (with a whisper of "bag of gold") retrieved the original bag. Then the bag went back into his left hand, to be dropped in again, and Harry's right hand went back into his pocket...

Professor McGonagall looked back at him once, but Harry managed to avoid freezing or flinching, and she didn't seem to notice anything. Though you never did quite know, with the adults that had a sense of humour. It took three iterations to get the job done, and Harry guessed he'd managed to steal maybe thirty Galleons from himself.

Harry reached up, wiped a bit of sweat from his forehead, and exhaled. "I'd like this one, please."

Fifteen Galleons lighter (twice the price of a wizard's wand, apparently) and one Moke Super Pouch QX31 heavier, Harry and Professor McGonagall pushed their way out of the door. The door formed a hand and waved goodbye to them as they left, extruding its arm in a way that made Harry feel a bit queasy.

And then, unfortunately...

"Are you really Harry Potter?" whispered the old man, one huge tear sliding down his cheek. "You wouldn't lie about that, would you? Only I'd heard rumours that you didn't really survive the Killing Curse and that's why no one ever heard from you again."

...it seemed that Professor McGonagall's disguise spell was less than perfectl...

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This is The Methods of Rationality, Part 1: Chapter 4: The Efficient Market Hypothesis, published by Eliezer Yudkowsky.

Disclaimer: J. K. Rowling is watching you from where she waits, eternally in the void between worlds.

A/N: As others have noted, the novels seem inconsistent in the apparent purchasing power of a Galleon; I'm picking a consistent value and sticking with it. Five pounds sterling to the Galleon doesn't square with seven Galleons for a wand and children using hand-me-down wands.

"World domination is such an ugly phrase. I prefer to call it world optimisation."

Heaps of gold Galleons. Stacks of silver Sickles. Piles of bronze Knuts.

Harry stood there, and stared with his mouth open at the family vault. He had so many questions he didn't know where to start.

From just outside the door of the vault, Professor McGonagall watched him, seeming to lean casually against the wall, but her eyes intent. Well, that made sense. Being plopped in front of a giant heap of gold coins was a test of character so pure it was archetypal.

"Are these coins the pure metal?" Harry said finally.

"What?" hissed the goblin Griphook, who was waiting near the door. "Are you questioning the integrity of Gringotts, Mr. Potter-Evans-Verres?"

"No," said Harry absently, "not at all, sorry if that came out wrong, sir. I just have no idea at all how your financial system works. I'm asking if Galleons in general are made of pure gold."

"Of course," said Griphook.

"And can anyone coin them, or are they issued by a monopoly that thereby collects seigniorage?"

"What?" said Professor McGonagall.

Griphook grinned, showing sharp teeth. "Only a fool would trust any but goblin coin!"

"In other words," Harry said, "the coins aren't supposed to be worth any more than the metal making them up?"

Griphook stared at Harry. Professor McGonagall looked bemused.

"I mean, suppose I came in here with a ton of silver. Could I get a ton of Sickles made from it?"

"For a fee, Mr. Potter-Evans-Verres." The goblin watched him with glittering eyes. "For a certain fee. Where would you find a ton of silver, I wonder?"

"I was speaking hypothetically," Harry said. For now, at any rate. "So... how much would you charge in fees, as a fraction of the whole weight?"

Griphook's eyes were intent. "I would have to consult my superiors..."

"Give me a wild guess. I won't hold Gringotts to it."

"A twentieth part of the metal would well pay for the coining."

Harry nodded. "Thank you very much, Mr. Griphook."

So not only is the wizarding economy almost completely decoupled from the Muggle economy, no one here has ever heard of arbitrage. The larger Muggle economy had a fluctuating trading range of gold to silver, so every time the Muggle gold-to-silver ratio got more than 5% away from the weight of seventeen Sickles to one Galleon, either gold or silver should have drained from the wizarding economy until it became impossible to maintain the exchange rate. Bring in a ton of silver, change to Sickles (and pay 5%), change the Sickles for Galleons, take the gold to the Muggle world, exchange it for more silver than you started with, and repeat.

Wasn't the Muggle gold to silver ratio somewhere around fifty to one? Harry didn't think it was seventeen, anyway. And it looked like the silver coins were actually smaller than the gold coins.

Then again, Harry was standing in a bank that literally stored your money in vaults full of gold coins guarded by dragons, where you had to go in and take coins out of your vault whenever you wanted to spend money. The finer points of arbitraging away market inefficiencies might well be lost on them. He'd been tempted to make snide remarks about the crudity of their financial system...

But the sad thing is, their way is probably better.

On the other hand, one competent hedge fundie could probably own the whole w...

Welcome to The Nonlinear Library, where we use Text-to-Speech software to convert the best writing from the Rationalist and EA communities into audio.

This is The Methods of Rationality, Part 3: Chapter 3: Comparing Reality To Its Alternatives, published by Eliezer Yudkowsky.

If J. K. Rowling asks you about this story, you know nothing.

"But then the question is - who?"

"Good Lord," said the barman, peering at Harry, "is this - can this be -?"

Harry leaned towards the bar of the Leaky Cauldron as best he could, though it came up to somewhere around the tips of his eyebrows. A question like that deserved his very best.

"Am I - could I be - maybe - you never know - if I'm not - but then the question is - who?"

"Bless my soul," whispered the old barman. "Harry Potter... what an honour."

Harry blinked, then rallied. "Well, yes, you're quite perceptive; most people don't realise that so quickly -"

"That's enough," Professor McGonagall said. Her hand tightened on Harry's shoulder. "Don't pester the boy, Tom, he's new to all this."

"But it is him?" quavered an old woman. "It's Harry Potter?" With a scraping sound, she got up from her chair.

"Doris -" McGonagall said warningly. The glare she shot around the room should have been enough to intimidate anyone.

"I only want to shake his hand," the woman whispered. She bent low and stuck out a wrinkled hand, which Harry, feeling confused and more uncomfortable than he ever had in his life, carefully shook. Tears fell from the woman's eyes onto their clasped hands. "My granson was an Auror," she whispered to him. "Died in seventy-nine. Thank you, Harry Potter. Thank heavens for you."

"You're welcome," Harry said automatically, and then he turned his head and shot Professor McGonagall a frightened, pleading look.

Professor McGonagall slammed her foot down just as the general rush was about to start. It made a noise that gave Harry a new referent for the phrase "Crack of Doom", and everyone froze in place.

"We're in a hurry," Professor McGonagall said in a voice that sounded perfectly, utterly normal.

They left the bar without any trouble.

"Professor?" Harry said, once they were in the courtyard. He had meant to ask what was going on, but oddly found himself asking an entirely different question instead. "Who was that pale man, by the corner? The man with the twitching eye?"

"Hm?" said Professor McGonagall, sounding a bit surprised; perhaps she hadn't expected that question either. "That was Professor Quirinus Quirrell. He'll be teaching Defence Against the Dark Arts this year at Hogwarts."

"I had the strangest feeling that I knew him..." Harry rubbed his forehead. "And that I shouldn't ought to shake his hand." Like meeting someone who had been a friend, once, before something went drastically wrong... that wasn't really it at all, but Harry couldn't find words. "And what was... all of that?"

Professor McGonagall was giving him an odd glance. "Mr. Potter... do you know... how much have you been told... about how your parents died?"

Harry returned a steady look. "My parents are alive and well, and they always refused to talk about how my genetic parents died. From which I infer that it wasn't good."

"An admirable loyalty," said Professor McGonagall. Her voice went low. "Though it hurts a little to hear you say it like that. Lily and James were friends of mine."

Harry looked away, suddenly ashamed. "I'm sorry," he said in a small voice. "But I have a Mum and Dad. And I know that I'd just make myself unhappy by comparing that reality to... something perfect that I built up in my imagination."

"That is amazingly wise of you," Professor McGonagall said quietly. "But your genetic parents died very well indeed, protecting you."

Protecting me?

Something strange clutched at Harry's heart. "What... did happen?"

Professor McGonagall sighed. Her wand tapped Harry's forehead, and his vision blurred for a moment. "Something of a disguise," she said, "so that this doesn't happen again, not until you're ...