CHAPTER ONE

 	The Search for the Letter      

 	It was just after dark one windy evening in the autumn of 18      . I was with my friend C. Auguste Dupin, in the library of his Paris apartment. For one hour at least we had been sitting in profound silence. Dupin seemed content just to watch the smoke rising from his pipe. As for myself, I was thinking about the affair of the Rue Morgue. More particularly I was thinking about how quickly Dupin had solved the case when the police could do nothing. It was therefore something of a coincidence when our old acquaintance Monsieur G of the Paris police arrived at the door.
 	G. explained that he had called to consult us, or rather to ask the opinion of my friend, about some official business that had caused a great deal of trouble.
 	"And what is the difficulty now?" I asked. "No more murders, I hope?"
 	"Oh no, nothing like that. The fact is, the business is very simple indeed, and I am sure we can manage it ourselves. But I thought Dupin would like to hear the details of the case, because it is so very odd."
 	"Simple and odd." said Dupin.
 	"Yes, in a way, though not exactly. The fact is, we have all been extremely puzzled because the affair is so simple and yet... we cannot understand it."
 	"Perhaps it is the very simplicity of the case which you do not understand," said my friend.
 	"What nonsense you talk sometimes, Monsieur Dupin," said the Prefect, laughing.
 	"Perhaps the mystery is a little too simple," Dupin continued.
 	"Oh good heavens! What an absurd idea!"
 	"A little too obvious."
 	"Ha! ha! ha!" laughed our visitor, deeply amused by Dupin's suggestion.
 	"And what after all is this business all about?" I asked.
 	"I will tell you in a few words," said the Prefect of police, "but before I begin I must warn you that this affair demands the greatest secrecy. If anybody knew that I was telling you about it, I would probably lose my job."
 	"Proceed," I said.
 	"Well then, I have received personal information from a very high official that a certain document of the utmost importance has been purloined from the royal apartments. The individual who took it is known; he was seen to take it. It is also known that he still has the document."
 	"How do you know this?" asked Dupin.
 	"We know, because of the nature of the document, and because if it had passed out of the robber's possession it would have certain... ahem... 'dramatic' consequences. Since these consequences have not yet arrived, we can assume that the robber still has the document.'
 	"Can't you be a little more explicit?" I said.
 	The policeman hesitated for a minute.
 	"If this document were revealed to a third person - an exalted personage whom I cannot name - it would cause grave damage to the honour and reputation of its owner - who is herself an important royal personage. This fact gives the robber power over her. He can use the document as a form of blackmail."
 	"But this power would depend on the robber knowing that the owner of the letter knew he had taken it." 
 	"The thief," said G. "is the Minister D, an unscrupulous individual. The method of the theft was ingenious. The document - it is a letter to be honest - had been received by the royal personage while she was alone in the royal bedroom. As she was reading it, she was suddenly interrupted by the entrance of her husband, the other personage I mentioned before, the person that she wanted to conceal it from. She tried to throw the letter into a drawer, without success, and so she was forced to lay it, open as it was, on a table. Fortunately only the side with the address on it was visible and so the letter was not noticed. It was then that the Minister D      entered. His sharp eye immediately perceived the letter and recognised the address. When he saw the anxious state of its owner, he knew at once her secret. After some routine business transactions, he produced from his pocket a letter similar to the one lying on the table and opened it, pretending to read the contents. He then casually placed his letter next to the one on the table and continued conversing with the lady and her husband about political matters. Then just before leaving the room he took the lady's letter from the table. Of course she saw him take it but she could say nothing. Her husband was standing next to her, and naturally she did not want him to know about the letter. And so the minister left the room with the vital document in his pocket, leaving his own letter - which was of no importance - upon the table."
 	"So it is true," said Dupin. "The robber knows that his victim saw him take the letter. He has her in his power."
 	"Yes," said the Prefect of Police. "And for the last few months he has been using that power for political purposes, to a very dangerous extent. The lady who was robbed is now convinced that she must get the letter back. But this cannot be done openly. That is why she has put me in charge of the case." 
 	"Quite right," said Dupin, through the smoke. "I cannot imagine that the Paris police has a better agent."
 	"You flatter me," said the Prefect, "but perhaps there is some truth in what you say."
 	"It is clear," said I, "that the minister still has the letter in his possession. If he used it it would no longer give him any power."
 	"True," said G. "and that is why I decided to conduct a meticulous search of the minister's house. The problem was how to search without his knowledge. It would be extremely dangerous if he realized we were looking for the letter. Fortunately for us the minister is often absent from home all night, and he does not have many servants. The servants' bedroom is quite far from the minister's rooms, and the servants are usually drunk at night.
 	"As you know, I have keys which can open any room or cabinet in Paris. So every night for the last three months we have been searching his house. But after all our efforts I must now conclude that the minister is a more astute individual than I am. I can assure you that we have investigated every corner of the premises, every little space where it would be possible to conceal the letter, but still we cannot find it."
 	"But is it not possible," I said, "that he has hidden it somewhere else, somewhere other than his own house?"
 	"No, I don't think that's very likely," said Dupin. "He needs to have the document near to him. It must be instantly available so that he can produce it whenever it becomes necessary to do so."
 	"If that is the case, then the letter must be somewhere in the minister's house. For it is not possible that it is on his person."
 	"Absolutely not," said the Prefect of Police. "My men have stopped and searched him twice under my own supervision."
 	"Obviously the man is not a complete fool," said Dupin. "He surely knew that he would be searched."
 	"Not a complete fool, no," said G. "But he is a poet, which I consider to be only one grade higher than a fool."
 	"Tell us the details of your search," I said. 
 	"Well, we took our time and we searched everywhere. I have a lot of experience in these matters. We divided the building into its separate rooms and for each of these rooms we spent an entire week searching. First we examined the furniture. We opened every possible drawer. To a well-trained police officer the existence of a secret drawer is impossible: there is only a certain amount of space in each cabinet. After the cabinets we examined the chairs. We probed the cushions with long needles. Then we removed the tops from the tables."
 	"Why did you do that?"
 	"Sometimes a person who wishes to conceal a document removes the top of a table and excavates one of the legs. He then pushes the document into the cavity and replaces the top. The bottoms and tops of bedposts are used in the same way."
 	"But you could not possibly remove - you could not dismantle all the pieces of furniture in which it would be possible to hide a letter. A letter can be rolled into a thin spiral tube, no thicker than a knitting needle. In this form it could be inserted into the rung of a chair for example. You did not dismantle all the chairs?" 
 	"Certainly not; but we did better - we examined the rungs of every chair in the house, and indeed the jointings of every other piece of furniture, with the help of a very powerful microscope. If there had been any changes in the jointings, any disorder in the glueing, we would have noticed it immediately."
 	"I presume you looked at the mirrors, between the frames and the glass plates, and also the beds and bedclothes as well as the curtains and carpets?"
 	"Of course; and when we had finished examining the furniture we searched the house itself. We divided its surface into numbered compartments; then we scrutinized each individual square centimetre of the house, and also of the two adjoining houses."
 	"The two adjoining houses!" I exclaimed. "You must have had a great deal of trouble."
 	"Yes we had, but the reward for finding the letter is very high."
 	"You included the grounds around the houses?"
 	"All the grounds are paved with brick. It was easy to search them. We simply had to check that the grass between the bricks was undisturbed."
 	"Of course you looked through papers and examined his books." 
 	''Certainly: we opened every file and turned over every page of every book. We also measured the thickness of each book cover and examined the bindings with the microscope. If any of the bindings had been altered in any way we would have noticed."
 	"You explored the floors beneath the carpets."
 	"Yes. We removed every carpet and examined the floorboards with the microscope."
 	"And the wallpaper?"
 	"Yes."
 	"You looked in the cellars?"
 	"Yes we did."
 	"Then." I said, "you have made a miscalculation and the letter is not in the house."
 	"I think you are right," said the Prefect. "And now Dupin, what do you think I should do?"
 	"I think you should search the house again."
 	"That would be absolutely pointless," said the Prefect. "I tell you, as sure as I live and breathe, the letter is not in the house."
 	"I have no better advice to give you," said Dupin. "I presume you have an accurate description of the letter."
 	"Oh yes!" said the Prefect. He took a notebook out of his pocket and began to read a detailed account of the internal, and especially of the external appearance of the stolen document. Soon afterwards, he thanked us for our time and left the apartment. He looked more depressed than I had ever seen him before.
 	 
 	CHAPTER two

 	Dupin's Techniques

 	About a month later, the Prefect paid us another visit. He found us occupied in the same manner as before. He sat down and began talking about the general business of the week.
 	After a few minutes I interrupted him:
 	"Well, but G, what about the Purloined Letter?"
 	The Prefect's face turned pale.
 	"I searched the house again, as Dupin suggested, but it was a waste of time, as I knew it would be."
 	"How much was the reward offered, did you say?" asked Dupin.
 	"A very large reward - a very liberal reward - I don't like to say how much; but I will say one thing, that I would give my own cheque for fifty thousand francs to anyone who could give me that letter. The fact is, the matter is becoming more and more urgent every day; the reward has recently been doubled. But even if it were trebled I could do no more than I have done already."
 	"Do you think so?" said Dupin. "I think, that there is some more that you could do to find the letter, eh?"
 	"How? - in what way?"
 	"You might, for example, take advice."
 	"My dear sir, I would happily pay for such advice. I would really give my fifty thousand francs to anyone who could help me."
 	"In that case," replied Dupin, "you can write me a cheque now. When you have signed it, I will give you the letter."
 	I was astonished. The Prefect appeared absolutely incredulous. For some minutes he remained silent and motionless, looking at my friend with open mouth and eyes that seemed to jump out from their sockets. Then he suddenly took a pen and after some hesitation signed a cheque for fifty thousand francs and gave it to Dupin. Dupin quickly examined the cheque and put it in his wallet. Then he opened a drawer in his desk and took a letter from it which he gave to the Prefect. The Prefect looked at the letter. His face was a perfect agony of joy as he opened it and quickly scanned its contents. Without saying another word, he ran out of the apartment still holding the letter in his hand.
 	When he had gone, Dupin began to explain.
 	"The Parisian police," he said, "are very capable in their way. They are persevering and ingenious and they know their job well.
 	When G recounted to us his mode of searching D's house, I was sure he had made a satisfactory investigation in as far as he was able."
 	"In as far as he was able?" I said.
 	"Yes. The techniques he used were not only the best of their kind, they were also executed to absolute perfection. If the letter had been hidden within the limits of G's search, he would certainly have discovered it."
 	I laughed, but Dupin seemed quite serious in all he was saying.
 	"The techniques," he continued, "were the best of their kind and were well executed. The problem was that they were not suitable for this case. They could not be applied to this particular thief. The Prefect has a set of extremely ingenious resources and he thinks he can use them to solve every single case in the same way. But he continually makes the mistake of being either too deep or too superficial, for the case in question; there are many schoolboys who are better thinkers than he is. I knew one about eight years of age who had great success in the game of 'even or odd'. This game is simple and is played with marbles. One player holds in his hand a number of marbles and asks the other player whether the number is even or odd. If his guess is right, the guesser wins one: if he is wrong he loses one. The boy I refer to won all the marbles of the school. Of course he had a principle which he used to make his guesses. He observed and measured the intelligence of his opponents. For example, let's imagine his opponent is a complete idiot. The idiot holds up his closed hand and asks the boy 'are they even or odd?' Our schoolboy replies 'odd' and loses; but the next time he wins. How does he do this? He simply says to himself, 'The idiot had them even the first time and his amount of intelligence is just sufficient to make him change them to odd the second time.' So he guesses odd and wins. Now with an idiot a degree more intelligent than the first he would reason like this: 'This boy sees that the first time I guess odd. Now the second time he will immediately propose a simple variation from even to odd, like the first idiot did.' But then a second thought will tell him that this variation is too simple, and finally he will decide to keep the marbles even as before. 'I will therefore guess even.' - he guesses even and wins. And so on. Now this method of reasoning which the other boys call 'luck' - what is it exactly?"
 	"It is simply a question of the boy trying to think like his opponent," I said.
 	"Precisely," said Dupin. "The boy identifies himself with his opponent's intellect."
 	"And the success of this identification depends on how accurately he can measure the intellect of his opponent?"
 	"Yes, for its practical value it depends on this," replied Dupin. "This is where the Prefect and his men make the mistake. They do not identify themselves with the intellect of their opponent. They do not even try to measure his intellect. They consider only their own ideas of ingenuity; and in searching for anything hidden, they consider only the ways in which they would have hidden it. In part they are right to do so, for their ingenuity is an accurate representation of that of the mass; but when the intelligence of the thief is greater than their own - and often when it is lower, their investigations fail. They have no variation in principle in their methods. The most they ever do is to extend or exaggerate these old methods, without considering the principles on which they are based. Let's look at the case of D. What did G do to vary the principle of action? What is all this drilling and probing and sounding and scrutinizing with the microscope and dividing the building into numbered square centimetres? It is simply the exaggeration of the application of one set of principles, which are based on the Prefect's own ideas about human ingenuity. He thinks that all men will hide a letter in the same way, not necessarily inside the leg of a chair, but in some place which is equally difficult to reach. But such hiding places are imagined only by ordinary intellects. In all cases of concealment, it is presumed that the article will be concealed in a place which is hard to find. Thus its discovery depends not upon the intelligence of the seekers but upon their patience, perseverance and determination. You will now understand what I meant when I said that the Prefect would surely have found the letter if it had been placed within the limits of his examination - in other words, if the principle of its concealment was the same as the principle of the Prefect's investigation. But the Prefect has been mystified, and the reason for his defeat is that he believes the minister to be a fool, simply because he is a poet. The Prefect thinks: all fools are poets, but that does riot mean that all poets are necessarily fools!"
 	"I thought it was the minister's brother who was the poet. The minister is a mathematician, isn't he?"
 	"No, he is both a mathematician and a poet. If he were just a mathematician he would not be able to reason well, and the Prefect would have found the letter."
 	"You surprise me when you say this. Mathematical reason has for centuries been regarded as the greatest form of reason."
 	"That is what mathematicians have made us believe, but it is an error."
 	"Explain."
 	"Mathematical axioms are not axioms of general truth, but only of relation. And something which may be true for relation - of form and quantity for example - is often completely false in terms of morality, or of human nature in general. To put it simply, in human nature the sum of the parts is rarely equal to the whole. In life, there is always something more, some unpredictable element that cannot be reduced to an equation."
 	"Whatever do you mean?" I said, laughing. By now I was completely confused.
 	"I mean to say," said Dupin, "that if the minister had been only a mathematician, the Prefect would have been able to keep the fifty thousand francs for himself. He would certainly have found the letter. But I knew the minister was also a poet. And so I tried to think like him, considering the circumstances he was in.
 	"Go on," I said.
 	"Remember that this man is a clever politician. He obviously knew the normal police procedures. He knew he would be searched and I'm sure he also knew that the police would search his house. The Prefect said that he was fortunate that the minister was often absent from the house at night. But I think that the minister was deliberately absent. He wanted the Prefect to search the house. It was all part of his plan. He wanted to make the police think that the letter was not in the house. So he let them search it from top to bottom. Finding nothing, the police would be convinced that the letter was not there. The minister must have known how the police conducted their searches. He must have known that the police would examine all the normal hiding places, all the places the Prefect told us about. So obviously he could not hide the letter in any of these places. I realized that because of this he would be forced to choose simplicity as the principle for hiding the letter. You remember how the Prefect laughed when I suggested that the problem of the mystery was perhaps the fact that it was too obvious."
 	"Yes," said I, "I remember it well." 
 	"There is a game," Dupin said, "which is played on a map. One of the players tells another to find a given word on the map - it could be the name of a town or a river or a monument - any word that appears on the map. Now a beginner immediately seeks the most difficult names with the most complicated spelling; but the expert selects those simple words which appear in huge letters and which stretch from one end of the map to the other. These, like street signs, are written in big letters, but they escape our attention, precisely because they are so excessively obvious. We simply don't see them."
 	"But what is the connection between this and the minister?"
 	"What is true of the physical world is also true of the moral world. This is something the Prefect cannot understand. He never once considered that the minister might have placed the letter right under his very nose, that he had perhaps hidden it in a very visible place, where nobody would think of looking for it. Or that perhaps the best way to hide the letter was not to hide it at all."

 	CHAPTER THREE

 	The Solution of the Case

 	With these ideas in my head I went to visit the minister at his house. I wore a pair of special green spectacles to aid my vision. As the minister told me about the political business of the day, I scrutinized his large writing table on which lay several papers and letters, as well as one or two books. But there was no trace of the purloined letter itself.
 	"As my eyes circled around the room I noticed a card-rack hanging from the centre of the mantlepiece. In this rack, which had five or six compartments, were a few visiting cards and a solitary letter. The letter was very soiled and crumpled and it was torn at the edge. It seemed as if someone had decided to tear it up but had then changed their mind. I looked closer to see what was written on it. It was addressed to the minister himself in female handwriting. The letter had been thrown carelessly into one of the compartments. 
 	"I knew immediately that this was the letter I was looking for. Certainly its appearance was completely different from the description of the stolen letter that the Prefect had given us. The wax seal of this letter was large and black with D's insignia inscribed on it, where as the purloined letter had a small red seal bearing the coat of arms of the Royal Family. This letter was addressed to D in a small female hand. The writing on the purloined letter was large and bold and it was addressed to a lady. But it seemed to me that these differences were excessive. The fact that this letter was almost the opposite of the letter the Prefect described made me suspicious. Then there was the fact that this letter was so clearly visible, in full view of every visitor. So visible, in fact, that nobody would see it, just like in the game I told you about."
 	"So what did you do?"
 	"I memorized the appearance of the letter and left the minister's house immediately, leaving a gold tobacco box on the writing table.
 	"The next morning I called at the minister's house again, saying that I had forgotten my tobacco. The minister seemed happy to see me again and we continued the conversation we had had the previous day. Suddenly we heard a loud noise coming from outside, the sound of a pistol shot followed by several screams. D ran to the window to see what was happening. In the meantime I went over to the card rack, took the letter, put it in my pocket and replaced it with a facsimile. "The disturbance in the street had been caused by a man with a gun. He had fired it above the heads of the crowd and everybody thought he was simply a lunatic or a drunk. In fact I had employed him to carry out this diversion to distract D and give me time to get the letter." 
 	"But why didn't you simply take it on your first visit?"
 	"D replied Dupin, "is a desperate and dangerous man. If I had taken the letter openly he would probably have had me killed before I could leave the building. But there was another reason. For eighteen months the minister has had the owner of the letter in his power. Now the situation is reversed. She has him in her power."
 	"How is that?"
 	"Because he still thinks he has the letter, thanks to my facsimile. He will proceed with his blackmail and his political career will be destroyed. It's ironic in a way too."
 	"In what way?"      
 	"It was the minister who gave me the idea of the facsimile, when he stole the original letter. To get the letter back I just did the same thing he did when he stole it. You could even say that between our letters there is a perfect, ahem... correspondence."
 	"Very funny."