Harry Potter and the Way of Reason

Disclaimer: J.K. Rowling watches you where she waits, eternally waiting in the void between worlds.

Author's statement: Others have pointed out that the original book has inconsistencies in the purchasing power of Galleons; I have chosen a value here as a unified standard for future.If a Galleon was worth five pounds, and a wand cost only seven Galleons, that didn't explain why there were still children using second-hand old wands.

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"World domination sucks. I prefer world optimization."

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Piles of Galleons.Row after row of silver Sickles.Copper Nat like a hill.

Harry stood there, mouth open, looking into his family storeroom.There are so many questions, it's hard to know which one to ask first.

Outside the warehouse door, Professor McGonagall watched him, seemingly casually leaning against the wall, but her eyes were focused.Anyway, it makes a lot of sense.Throwing someone in front of a pile of gold coins is such a test of character that the test has become a classic.

"Are these coins made of pure metal?" Harry asked finally.

"What?" Griphook the goblin waited by the door dissatisfied, "Are you questioning the integrity of Gringotts, Mr. Potter-Evans-Verys?"

"No," Harry said absently. "Not at all. I'm sorry to misunderstand you, sir. I just don't understand how your financial system works. What I want to ask is whether, under normal circumstances, gold Galleons are made of pure gold."

"Of course," said Griphook.

"Can anyone mint coins, or is there a dedicated department that issues them and collects seigniorage?"

"What?" asked Professor McGonagall.

Griphook smiled, showing his pointed teeth. "Except for fools, who would dare to believe that the money wasn't made by goblins!"

"In other words," said Harry, "these coins aren't worth more than the metal they're minted in?"

Griphook stared at Harry.Professor McGonagall looked bewildered.

"I mean, suppose I come here with a ton of silver. Can I exchange that silver for a ton of silver Sickles?"

"There will be a charge for that, Mr. Potter Evans-Verys." The goblin looked at him intently. "There will be a fee. I'm curious, where did you get a ton of silver?"

"I'm just using an analogy," Harry said.At least for now. "So... how much is the cost, if calculated as a proportion of the total weight?"

Griphook's eyes were alert. "I need to ask my superiors..."

"You can take a wild guess. I won't ask Gringotts to comply."

"A twentieth part of the metal is enough to pay the minting fee."

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

So not only is the economy of the wizarding world almost completely disconnected from that of the Muggle world, but no one here has ever heard of arbitrage. [2] In the wider Muggle world, the exchange ratio of gold and silver is floating, so whenever the Muggle gold-silver exchange ratio and the weight ratio of seventeen silver Sickles to one gold Galleon differ by more than 5% At that time, Gold Galleons or Silver Sickles will flow out of the wizarding world until the current exchange rate cannot be maintained.Bring a ton of silver, exchange it for silver Sickles (and pay a 5% handling fee), exchange the silver Sickles for Gold Galleons, take the gold to the Muggle world, exchange it for more silver, and so on.

Isn't the gold-silver ratio in the Muggle world about fifty to one?Harry didn't think it was seventeen to one anyway.These silver coins look smaller than gold coins.

Having said that, the bank Harry is in is the kind of place that really stores your money in a vault full of gold coins, guarded by dragons, and every time you want to spend money, you have to come in and take the coins out of the vault .The details of stripping out inefficient markets with arbitrage trades may have been beyond their comprehension.He'd love to have a few digs at this primitive financial system...

Sadly though, maybe their way is better.

On the other hand, a competent hedge fund clerk might hold the finances of the entire wizarding world in his hands in a week.Harry took this to heart in case he ran out of money in the future, or happened to be free for a week.

Before that, the large pile of gold coins in Potter's treasury should be enough for him to spend in the near future.

Harry stepped forward and began to pick up the coins in one hand and put them in the other.

When he got twenty, Professor McGonagall coughed. "I think these are more than enough for your school supplies, Mr. Potter."

"Huh?" Harry said absently. "Wait a minute, I'm doing a Fermi calculation."[3]

"A what?" asked Professor McGonagall, sounding wary.

"A mathematical thing. Named after Enrico Fermi. A way to mentally estimate approximate results quickly..."

Twenty gold Galleons are almost one-tenth of a kilogram?Then the price of gold is about 200 pounds per kilogram?So a galleon is worth about fifty pounds...the stacks of gold coins look like they would be about sixty high and the bottom side about twenty wide, in a pyramid shape, so the total volume is one-third of the corresponding cube.In this way, one pile is about [-] Galleons, and there are five piles in total, so the total is [-] Galleons, or [-] million pounds.

nice.Harry gave a cold, satisfied smile.It was a pity that he was too busy exploring this amazing new world of magic to study what the world of the rich was like.A quick Fermi calculation told him that the latter was about a billion times less interesting than the former.

But anyway, I don't have to mow someone else's grass for a damned pound anymore.

Harry turned away from the pile of money. "Forgive me for asking, Professor McGonagall, but I remember my parents being in their twenties when they died. Is it common in the wizarding world for a young couple to have this much money?" It will cost five thousand pounds.The first rule of economics: money can't be eaten.

Professor McGonagall shook his head. "Your father is the last heir of an ancient family, Mr. Potter. It is also possible..." The witch hesitated. "Some of the money may also be a bounty on 'the man', to be paid to the man who kills—, ah, beat him. Or maybe those bounties haven't been paid yet. I don't know."

"Interesting..." Harry said slowly. "So some of it is really mine in a way. I mean, I earned it. In a way. Possibly. Even if I don't remember it myself." Harry's finger Tapped the pant leg. "In this way, I won't feel too guilty for spending a little bit! Take it easy, Professor McGonagall!"

"Mr. Potter! You are not yet of age, so I can only allow you to withdraw a reasonable amount of money—"

"I will definitely be reasonable! I fully agree that budgeting should be cautious, and you should not buy impulsively! But I really saw something on the way, which is completely wise and mature consumption..."

Harry and Professor McGonagall stared at each other in a silent staring contest.

"Like?" said Professor McGonagall at last.

"A box with more space inside than outside?"

Professor McGonagall's expression became severe. "That kind of chest is expensive, Mr. Potter!"

"I know, but—" Harry pleaded. "I'm sure I'll want one when I grow up. And I can afford it. Logically, it makes more sense to buy it now than later, so I can use it right away. It's all about the money anyway." Expensive, isn't it? I mean, I'll buy a nice one with a lot of space in it so I don't have to spend money on upgrades later on..." Harry paused hopefully.

Professor McGonagall's gaze did not waver. "What are you going to put in a box like that, Mr. Potter—"

"Book."

"I knew it," sighed Professor McGonagall.

"You should have told me that this magic item exists! And that I can afford it! Now my dad and I are going to spend the next two days going to all the second-hand bookstores looking for old textbooks so I can Hogwarts could have a decent science library too - maybe a little sci-fi collection, if I can find good books in the bargain bins. How about that, I'll let you How about some benefits too? Let me buy—”

"Mr. Potter! Do you think you can bribe me?"

"What? No! I didn't mean that! I just said that Hogwarts can keep some of the books I brought, if you think there are any books I brought that are suitable for adding to your library. I will Try to buy as cheap as possible, I just want to see it when I want to. Bribes with books are all right, aren't they? That's our—"

"Family tradition."

"Yes, exactly."

Professor McGonagall's body doesn't seem to be as tall and straight as before, and the shoulders under the black robe hang down. "I can't deny that you have a point, though I wish I could. I allow you to take out another hundred Galleons, Mr. Potter." She sighed again. "I know I'm going to regret it, but let it go."

"That's it! And does the 'Mock Bag' really have the function I understand?" [4]

"It's not as useful as a box," the witch said with obvious reluctance, "However, the moke bag is imbued with the fetch spell and the expansion spell that makes it impossible for outsiders to detect it, and it can be used to store a certain number of things. Only those who go in can take it out—"

"Great! I absolutely need one! This is like an absolutely perfect super fanny pack! Batman's tool storage belt! I don't need a swiss army knife anymore, I can fit a whole toolbox in it! And books I can put three of the books I'm reading in there so I can take one out and read it anytime, anywhere! I'll never waste a minute of my life again! What do you think, Professor McGonagall? This is for It is the best reason for children to study."

"...I think you can take ten more Galleons."

Griphook looked at Harry with frank admiration, almost total admiration.

"And a little pocket money, as you said earlier. I remember seeing one or two things that would fit nicely in a mok bag."

"Don't push yourself too far, Mr. Potter."

"But, oh, Professor McGonagall, why did you let me down when I was the happiest? Today is such a happy day, I saw so many magic props for the first time! Why do you have to play that grumpy adult, Instead of smiling at me when I bought my beloved toy, and remembering your own innocent childhood, with only a paltry portion of my fortune, and the best I've ever beaten in England Did the dreaded wizard win it? I don't mean you're ungrateful, but really, what are a few toys compared to this?"

"You," growled Professor McGonagall.The look on her face was so frightening and terrifying that Harry backed away with a small cry of surprise, knocking over a pile of gold coins, and lay sprawled on top of it with a jingling sound.Griphook sighed, covering his face with his paws. "I think I might as well lock you up in this storeroom, Mr Potter. That would be a great service to the British wizarding community."

Then they left without further trouble.

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1. Efficient market hypothesis: baike.baidu/view/342791.htm

2. Arbitrage trading: baike.baidu/subview/876684/9896155.htm

3. Fermi calculation: lesswrong/lw/h5e/fermi_estimates/

4. Moke pouch: According to the book Fantastic Beasts and Where to Find Them, a moke is a shape-shifting lizard.A mokeskinpouch is supposed to be a bag made from the hide of this shape-shifting lizard.

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