“I presume you looked to the mirrors, between the boards and the plates, and you probed the beds and the bedclothes, as well as the curtains and carpets.”
“That of course; and when we had absolutely completed every particle of the furniture in this way, then we examined the house itself. We divided its entire surface into compartments, which we numbered, so that none might be missed; then we scrutinized each individual square inch throughout the premises, including the two houses immediately adjoining, with the microscope, as before.”
“The two houses adjoining!” I exclaimed; “you must have had a great deal of trouble.”
“We had; but the reward offered is prodigious.”
“You include the grounds about the houses?”
“All the grounds are paved with brick. They gave us comparatively little trouble. We examined the moss between the bricks, and found it undisturbed.”
“You looked among D——’s papers, of course, and into the books of the library?”
“Certainly; we opened every package and parcel; we not only opened every book, but we turned over every leaf in each volume, not contenting ourselves with a mere shake, according to the fashion of some of our police officers. We also measured the thickness of every book-cover, with the most accurate admeasurement, and applied to each the most jealous scrutiny of the microscope. Had any of the bindings been recently meddled with, it would have been utterly impossible that the fact should have escaped observation. Some five or six volumes, just from the hands of the binder, we carefully probed, longitudinally, with the needles.”
“You explored the floors beneath the carpets?”
“Beyond doubt. We removed every carpet, and examined the boards with the microscope.”
“And the paper on the walls?”
“Yes.”
“You looked into the cellars?”
“We did.”
“Then,” I said, “you have been making a miscalculation, and the letter is not upon the premises, as you suppose.”
“I fear you are right there,” said the Prefect. “And now, Dupin, what would you advise me to do?”
“To make a thorough research of the premises.”
“That is absolutely needless,” replied G——. “I am not more sure that I breathe than I am that the letter is not at the hotel.”
“I have no better advice to give you,” said Dupin. “You have, of course, an accurate description of the letter?”
“Oh, yes!”—And here the Prefect, producing a memorandum-book, proceeded to read aloud a minute account of the internal, and especially of the external appearance of the missing document. Soon after finishing the perusal of this description, he took his departure, more entirely depressed in spirits than I had ever known the good gentleman before.
In about a month afterward he paid us another visit, and found us occupied very nearly as before. He took a pipe and a chair and entered into some ordinary conversation. At length I said:
“Well, but G——, what of the purloined letter? I presume you have at last made up your mind that there is no such thing as overreaching the Minister?”
“Confound him, say I—yes; I made the re-examination, however, as Dupin suggested—but it was all labor lost, as I knew it would be.”
“How much was the reward offered, did you say?” asked Dupin.
“Why, a very great deal—a very liberal reward—I don’t like to say how much, precisely; but one thing I will say, that I wouldn’t mind giving my individual check for fifty thousand francs to any one who could obtain me that letter. The fact is, it is becoming of more and more importance every day; and the reward has been lately doubled. If it were trebled, however, I could do no more than I have done.”
“Why, yes,” said Dupin, drawlingly between the whiffs of his meerschaum. “I really—think, G——, you have not exerted yourself—to the utmost in this matter. You might—do a little more, I think, eh?”
“How?—in what way?”
“Why—puff, puff—you might—puff, puff—employ counsel in the matter, eh?—puff, puff, puff. Do you remember the story they tell of Abernethy?”
“No; hang Abernethy!”
“To be sure! hang him and welcome. But, once upon a time, a certain rich miser conceived the design of sponging upon this Abernethy for a medical opinion. Getting up, for this purpose, an ordinary conversation in a private company, he insinuated his case to the physician, as that of an imaginary individual.
“‘We will suppose,’ said the miser, ‘that his symptoms are such and such; now, doctor, what would you have directed him to take?’
“‘Take!’ said Abernethy, ‘why, take advice, to be sure.’ ”
“But,” said the Prefect, a little discomposed, “I am perfectly willing to take advice, and to pay for it. I would really give fifty thousand francs to any one who would aid me in the matter.”
“In that case,” replied Dupin, opening a drawer, and producing a check-book, “you may as well fill me up a check for the amount mentioned. When you have signed it, I will hand you the letter.”
I was astounded. The Prefect appeared absolutely thunder-stricken. For some minutes he remained speechless and motionless, looking incredulously at my friend with open mouth, and eyes that seemed starting from their sockets; then apparently recovering himself in some measure, he seized a pen, and after several pauses and vacant stares, finally filled up and signed a check for fifty thousand francs, and handed it across the table to Dupin. The latter examined it carefully and deposited it in his pocket-book; then, unlocking an escritoire, took thence a letter and gave it to the Prefect. This functionary grasped it in a perfect agony of joy, opened it with a trembling hand, cast a rapid glance at its contents, and then scrambling and struggling to the door, rushed at length unceremoniously from the room and from the house, without having uttered a syllable since Dupin had requested him to fill up the check.
When he had gone, my friend entered into some explanations.
“The Parisian police,” he said, “are exceedingly able in their way. They are persevering, ingenious, cunning, and thoroughly versed in the knowledge which their duties seem chiefly to demand. Thus, when G—— detailed to us his mode of searching the premises at the Hotel D——, I felt entire confidence in his having made a satisfactory investigation—so far as his labors extended.”
“So far as his labors extended?” said I.
“Yes,” said Dupin. “The measures adopted were not only the best of their kind, but carried out to absolute perfection. Had the letter been deposited within the range of their search, these fellows would, beyond a question, have found it.”
I merely laughed—but he seemed quite serious in all that he said.
“The measures then,” he continued, “were good in their kind, and well executed; their defect lay in their being inapplicable to the case and to the man. A certain set of highly ingenious resources are, with the Prefect, a sort of Procrustean bed, to which he forcibly adapts his designs. But he perpetually errs by being too deep or too shallow for the matter in hand; and many a schoolboy is a better reasoner than he. I knew one about eight years of age, whose success at guessing in the game of ‘even and odd’ attracted universal admiration. This game is simple, and is played with marbles. One player holds in his hand a number of these toys, and demands of another whether that number is even or odd. If the guess is right, the guesser wins one; if wrong, he loses one. The boy to whom I allude won all the marbles of the school. Of course he had some principle of guessing; and this lay in mere observation and admeasurement of the astuteness of his opponents. For example, an arrant simpleton is his opponent, and, holding up his closed hand, asks, ‘Are they even or odd?’ Our schoolboy replies, ‘Odd,’ and loses; but upon the second trial he wins, for he then says to himself: ‘The simpleton had them even upon the first trial, and his amount of cunning is just sufficient to make him have them odd upon the second; I will therefore guess odd’;—he guesses odd, and wins. Now, with a s
impleton a degree above the first, he would have reasoned thus: ‘This fellow finds that in the first instance I guessed odd, and, in the second, he will propose to himself, upon the first impulse, a simple variation from even to odd, as did the first simpleton; but then a second thought will suggest that this is too simple a variation, and finally he will decide upon putting it even as before. I will therefore guess even’;—he guesses even, and wins. Now this mode of reasoning in the schoolboy, whom his fellows termed ‘lucky,’—what, in its last analysis, is it?”
“It is merely,” I said, “an identification of the reasoner’s intellect with that of his opponent.”
“It is,” said Dupin; “and, upon inquiring of the boy by what means he effected the thorough identification in which his success consisted, I received answer as follows: ‘When I wish to find out how wise, or how stupid, or how good, or how wicked is any one, or what are his thoughts at the moment, I fashion the expression of my face, as accurately as possible, in accordance with the expression of his, and then wait to see what thoughts or sentiments arise in my mind or heart, as if to match or correspond with the expression.’ This response of the schoolboy lies at the bottom of all the spurious profundity which has been attributed to Rochefoucault, to La Bougive, to Machiavelli, and to Campanella.”
“And the identification,” I said, “of the reasoner’s intellect with that of his opponent, depends, if I understand you aright, upon the accuracy with which the opponent’s intellect is admeasured.”
“For its practical value it depends upon this,” replied Dupin; “and the Prefect and his cohort fail so frequently, first by default of his identification, and, secondly, by ill-admeasurement, or rather through non-admeasurement, of the intellect with which they are engaged. They consider only their own ideas of ingenuity; and, in searching for anything hidden advert only to the modes in which they would have hidden it. They are right in this much—that their own ingenuity is a faithful representative of that of the mass; but when the cunning of the individual felon is diverse in character from their own, the felon foils them, of course. This always happens when it is above their own, and very usually when it is below. They have no variation of principle in their investigations; at best, when urged by some unusual emergency—by some extraordinary reward—they extend or exaggerate their old modes of practice, without touching their principles. What, for example, in this case of D——, has been done to vary the principle of action? What is all this boring, and probing, and sounding, and scrutinizing with the microscope, and dividing the surface of the building into registered square inches—what is it all but an exaggeration of the application of the one principle or set of principles of search, which are based upon the one set of notions regarding human ingenuity, to which the Prefect, in the long routine of his duty, has been accustomed? Do you not see he has taken it for granted that all men proceed to conceal a letter—not exactly in a gimlet-hole bored in a chair-leg, but, at least, in some out-of-the-way hole or corner suggested by the same tenor of thought which would urge a man to secrete a letter in a gimlet-hole bored in a chair-leg? And do you not see also that such recherchés nooks for concealment are adapted only for ordinary occasions, and would be adopted only by ordinary intellects; for, in all cases of concealment, a disposal of the article concealed—a disposal of it in this recherché manner,—is in the very first instance, presumable and presumed; and thus its discovery depends, not at all upon the acumen, but altogether upon the mere care, patience, and determination of the seekers; and where the case is of importance—or, what amounts to the same thing in the political eyes, when the reward is of magnitude,—the qualities in question have never been known to fail. You will now understand what I meant in suggesting that, had the purloined letter been hidden anywhere within the limits of the Prefect’s examination—in other words, had the principle of its concealment been comprehended within the principles of the Prefect—its discovery would have been a matter altogether beyond question. This functionary, however, has been thoroughly mystified; and the remote source of his defeat lies in the supposition that the Minister is a fool, because he has acquired renown as a poet. All fools are poets; this the Prefect feels; and he is merely guilty of a non distributio medii in thence inferring that all poets are fools.”
“But is this really the poet?” I asked. “There are two brothers, I know; and both have attained reputation in letters. The minister I believe has written learnedly on the Differential Calculus. He is a mathematician, and no poet.”
“You are mistaken; I know him well; he is both. As poet and mathematician, he would reason well; as mere mathematician, he could not have reasoned at all, and thus would have been at the mercy of the Prefect.”
“You surprise me,” I said, “by these opinions, which have been contradicted by the voice of the world. You do not mean to set at naught the well-digested idea of centuries. The mathematical reason has long been regarded as the reason par excellence.”
“‘Il y a parier,’ ” replied Dupin, quoting from Chamfort, “‘que toute idée publique, toute convention reçue, est une sottise, car elle a convenue au plus grand nombre.’ The mathematicians, I grant you, have done their best to promulgate the popular error to which you allude, and which is none the less an error for its promulgation as truth. With an art worthy a better cause, for example, they have insinuated the term ‘analysis’ into application to algebra. The French are the originators of this particular deception; but if a term is of any importance—if words derive any value from applicability—then ‘analysis’ conveys ‘algebra’ about as much as, in Latin, ‘ambitus’ implies ‘ambition,’ ‘religio’ ‘religion,’ or ‘homines honesti’ a set of honorable men.”
“You have a quarrel on hand, I see,” said I, “with some of the algebraists of Paris; but proceed.”
“I dispute the availability, and thus the value, of that reason which is cultivated in any especial form other than the abstractly logical. I dispute, in particular, the reason educed by mathematical study. The mathematics are the science of form and quantity; mathematical reasoning is merely logic applied to observation upon form and quantity. The great error lies in supposing that even the truths of what is called pure algebra are abstract or general truths. And this error is so egregious that I am confounded at the universality with which it has been received. Mathematical axioms are not axioms; of general truth. What is true of relation—of form and quantity—is often grossly false in regard to morals, for example. In this latter science it is very usually untrue that the aggregated parts are equal to the whole. In chemistry also the axiom fails. In the consideration of motive it fails; for two motives, each of a given value, have not, necessarily, a value when united, equal to the sum of their values apart. There are numerous other mathematical truths which are only truths within the limits of relation. But the mathematician argues from his finite truths, through habit, as if they were of an absolutely general applicability—as the world indeed imagines them to be. Bryant, in his very learned ‘Mythology,’ mentions an analogous source of error, when he says that ‘although the Pagan fables are not believed, yet we forget ourselves continually, and make inferences from them as existing realities.’ With the algebraists, however, who are Pagans themselves, the ‘Pagan fables’ are believed, and the inferences are made, not so much through lapse of memory as through an unaccountable addling of the brains. In short, I never yet encountered the mere mathematician who could be trusted out of equal roots, or one who did not clandestinely hold it as a point of his faith that x2 + px was absolutely and unconditionally equal to q. Say to one of these gentlemen, by way of experiment, if you please, that you believe occasions may occur where x2 + px is not altogether equal to q, and, having made him understand what you mean, get out of his reach as speedily as convenient, for, beyond doubt, he will endeavor to knock you down.
“I mean to say,” continued Dupin, while I merely laughed at his last observations, “that if the Minister had been no more than a mathematician, the P
refect would have been under no necessity of giving me this check. I knew him, however, as both mathematician and poet, and my measures were adapted to his capacity, with reference to the circumstances by which he was surrounded. I knew him as a courtier, too, and as a bold intriguant. Such a man, I considered, could not fail to be aware of the ordinary political modes of action. He could not have failed to anticipate—and events have proved that he did not fail to anticipate—the waylayings to which he was subjected. He must have foreseen, I reflected, the secret investigations of his premises. His frequent absences from home at night, which were hailed by the Prefect as certain aids to his success, I regarded only as ruses, to afford opportunity for thorough search to the police, and thus the sooner to impress them with the conviction to which G——, in fact, did finally arrive—the conviction that the letter was not upon the premises. I felt, also, that the whole train of thought, which I was at some pains in detailing to you just now, concerning the invariable principle of political action in searches for articles concealed—I felt that this whole train of thought would necessarily pass through the mind of the Minister. It would imperatively lead him to despise all the ordinary nooks of concealment. He could not, I reflected, be so weak as not to see that the most intricate and remote recess of his hotel would be as open as his commonest closets to the eyes, to the probes, to the gimlets, and to the microscopes of the Prefect. I saw, in fine, that he would be driven, as a matter of course, to simplicity, if not deliberately induced to it as a matter of choice. You will remember, perhaps, how desperately the Prefect laughed when I suggested, upon our first interview, that it was just possible this mystery troubled him so much on account of its being so very self-evident.”