The Science of Deduction Sherlock Holmes took his bottle from the corner of the mantel-piece and his hypodermic syringe from its neat morocco case. With his long, white, nervous fingers he adjusted the delicate needle, and rolled back his left shirt-cuff. For some little time his eyes rested thoughtfully upon the sinewy forearm and wrist all dotted and scarred with innumerable puncture-marks. Finally he thrust the sharp point home, pressed down the tiny piston, and sank back into the velvet-lined arm-chair with a long sigh of satisfaction.
Three times a day for many months I had witnessed this performance, but custom had not reconciled my mind to it. On the contrary, from day to day I had become more irritable at the sight, and my conscience swelled nightly within me at the thought that I had lacked the courage to protest. Again and again I had ed a vow that I should deliver my soul upon the subject, but there was that in the cool, nonchalant air of my companion which made him the last man with whom one would care to take anything approaching to a liberty. His great powers, his masterly manner, and the experience which I had had of his many extraordinary qualities, all made me diffident and backward in crossing him.
Yet upon that afternoon, whether it was the Beaune which I had taken with my lunch, or the additional exasperation produced by the extreme deliberation of his manner, I suddenly felt that I could hold out no longer. "Which is it to-day?" I asked,—"morphine or cocaine?"
He raised his eyes languidly from the old black-letter volume which he had opened. "It is cocaine," he said,—"a seven-per-cent. solution. Would you care to try it?"
"No, indeed," I answered, brusquely. "My constitution has not got over the Afghan campaign yet. I cannot afford to throw any extra strain upon it."
He smiled at my vehemence. "Perhaps you are right, Watson," he said. "I suppose that its influence is physically a bad one. I find it, however, so transcendently stimulating and clarifying to the mind that its secondary action is a matter of small moment." "But consider!" I said, earnestly. "Count the cost! Your brain may, as you say, be roused and excited, but it is a pathological and morbid process, which involves increased tissue-change and may at last leave a permanent weakness. You know, too, what a black reaction comes upon you. Surely the game is hardly worth the candle. Why should you, for a mere ing pleasure, risk the loss of those great powers with which you have been endowed? that I speak not only as one comrade to another, but as a medical man to one for whose constitution he is to some extent answerable." He did not seem offended. On the contrary, he put his finger-tips together and leaned his elbows on the arms of his chair, like one who has a relish for conversation. "My mind," he said, "rebels at stagnation. Give me problems, give me work, give me the most abstruse cryptogram or the most intricate analysis, and I am in my own proper atmosphere. I can dispense then with artificial stimulants. But I abhor the dull routine of existence. I crave for mental exaltation. That is why I have chosen my own particular profession,—or rather created it, for I am the only one in the world."
"The only unofficial detective?" I said, raising my eyebrows.
"The only unofficial consulting detective," he answered. "I am the last and highest court of appeal in detection. When Gregson or Lestrade or Athelney Jones are out of their depths—which, by the way, is their normal state—the matter is laid before me. I examine the data, as an expert, and pronounce a specialist's opinion. I claim no credit in such cases. My name figures in no newspaper. The work itself, the pleasure of finding a field for my peculiar powers, is my highest reward. But you have yourself had some experience of my methods of work in the Jefferson Hope case."
"Yes, indeed," said I, cordially. "I was never so struck by anything in my life. I even embodied it in a small brochure with the somewhat fantastic title of 'A Study in Scarlet.'"
He shook his head sadly. "I glanced over it," said he. "Honestly, I cannot congratulate you upon it. Detection is, or ought to be, an exact science, and should be treated in the same cold and unemotional manner. You have attempted to tinge it with romanticism, which produces much the same effect as if you worked a love-story or an elopement into the fifth proposition of Euclid."
"But the romance was there," I remonstrated. "I could not tamper with the facts."
"Some facts should be suppressed, or at least a just sense of proportion should be observed in treating them. The only point in the case which deserved mention was the curious analytical reasoning from effects to causes by which I succeeded in unraveling it."
I was annoyed at this criticism of a work which had been specially designed to please him. I confess, too, that I was irritated by the egotism which seemed to demand that every line of my pamphlet should be devoted to his own special doings. More than once during the years that I had lived with him in Baker Street I had observed that a small vanity underlay my companion's quiet and didactic manner. I made no remark, however, but sat nursing my wounded leg. I had a Jezail bullet through it some time before, and, though it did not prevent me from walking, it ached wearily at every change of the weather.
"My practice has extended recently to the Continent," said Holmes, after a while, filling up his old brier-root pipe.
"I was consulted last week by Francois Le Villard, who, as you probably know, has come rather to the front lately in the French detective service. He has all the Celtic power of quick intuition, but he is deficient in the wide range of exact knowledge which is essential to the higher developments of his art. The case was concerned with a will, and possessed some features of interest. I was able to refer him to two parallel cases, the one at Riga in 1857, and the other at St. Louis in 1871, which have suggested to him the true solution. Here is the letter which I had this morning acknowledging my assistance." He tossed over, as he spoke, a crumpled sheet of foreign notepaper. I glanced my eyes down it, catching a profusion of notes of iration, with stray "magnifiques," "coup-de-maitres," and "tours-de-force," all testifying to the ardent iration of the Frenchman. "He speaks as a pupil to his master," said I.
"Oh, he rates my assistance too highly," said Sherlock Holmes, lightly. "He has considerable gifts himself. He possesses two out of the three qualities necessary for the ideal detective. He has the power of observation and that of deduction. He is only wanting in knowledge; and that may come in time. He is now translating my small works into French."
"Your works?"
"Oh, didn't you know?" he cried, laughing. "Yes, I have been guilty of several monographs. They are all upon technical subjects. Here, for example, is one 'Upon the Distinction between the Ashes of the Various Tobaccoes.' In it I enumerate a hundred and forty forms of cigar-, cigarette-, and pipe-tobacco, with colored plates illustrating the difference in the ash. It is a point which is continually turning up in criminal trials, and which is sometimes of supreme importance as a clue. If you can say definitely, for example, that some murder has been done by a man who was smoking an Indian lunkah, it obviously narrows your field of search. To the trained eye there is as much difference between the black ash of a Trichinopoly and the white fluff of bird's-eye as there is between a cabbage and a potato."
"You have an extraordinary genius for minutiae," I remarked.
"I appreciate their importance. Here is my monograph upon the tracing of footsteps, with some remarks upon the uses of plaster of Paris as a preserver of impresses. Here, too, is a curious little work upon the influence of a trade upon the form of the hand, with lithotypes of the hands of slaters, sailors, corkcutters, compositors, weavers, and diamond-polishers. That is a matter of great practical interest to the scientific detective,—especially in cases of unclaimed bodies, or in discovering the antecedents of criminals. But I weary you with my hobby."
"Not at all," I answered, earnestly. "It is of the greatest interest to me, especially since I have had the opportunity of observing your practical application of it. But you spoke just now of observation and deduction. Surely the one to some extent implies the other."
"Why, hardly," he answered, leaning back luxuriously in his arm-chair, and sending up thick blue wreaths from his pipe. "For example, observation shows me that you have been to the Wigmore Street Post-Office this morning, but deduction lets me know that when there you dispatched a telegram."
"Right!" said I. "Right on both points! But I confess that I don't see how you arrived at it. It was a sudden impulse upon my part, and I have mentioned it to no one."
"It is simplicity itself," he remarked, chuckling at my surprise,—"so absurdly simple that an explanation is superfluous; and yet it may serve to define the limits of observation and of deduction. Observation tells me that you have a little reddish mould adhering to your instep. Just opposite the Seymour Street Office they have taken up the pavement and thrown up some earth which lies in such a way that it is difficult to avoid treading in it in entering. The earth is of this peculiar reddish tint which is found, as far as I know, nowhere else in the neighborhood. So much is observation. The rest is deduction."
"How, then, did you deduce the telegram?" "Why, of course I knew that you had not written a letter, since I sat opposite to you all morning. I see also in your open desk there that you have a sheet of stamps and a thick bundle of post-cards. What could you go into the post-office for, then, but to send a wire? Eliminate all other factors, and the one which remains must be the truth." |
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La ciencia del razonamiento deductivo Sherlock Holmes cogi el frasco de la esquina de la repisa de la chimenea y sac la jeringuilla hipodrmica de su elegante estuche de tafilete. Ajust la delicada aguja con sus largos, blancos y nerviosos dedos y se remang la manga izquierda de la camisa. Durante unos momentos, sus ojos pensativos se posaron en el fibroso antebrazo y en la mueca, marcados por las cicatrices de innumerables pinchazos. Por ltimo, clav la afilada punta, apret el minsculo mbolo y se ech hacia atrs, hundindose en la butaca tapizada de terciopelo con un largo suspiro de satisfaccin.
Yo llevaba muchos meses presenciando esta escena tres veces al da, pero la costumbre no haba logrado que mi mente la aceptara. Por el contrario, cada da me irritaba ms contemplarla, y todas las noches me remorda la conciencia al pensar que me faltaba valor para protestar. Una y otra vez me haca el propsito de decir lo que pensaba del asunto, pero haba algo en los modales fros y despreocupados de mi compaero que lo converta en el ltimo hombre con el que uno querra tomarse algo parecido a una libertad.
Su enorme talento, su actitud dominante y la experiencia que yo tena de sus muchas y extraordinarias cualidades me impedan decidirme a enfrentarme con l.
Sin embargo, aquella tarde, tal vez a causa del "Beaune" que haba bebido en la comida, o tal vez por la irritacin adicional que me produjo lo descarado de su conducta, sent de pronto que ya no poda aguantar ms.
––Qu ha sido hoy? ––pregunt––. Morfina o cocana? Holmes levant con languidez la mirada del viejo volumen de caracteres gticos que acababa de abrir.
––Cocana ––dijo––, disuelta al siete por ciento. Le apetece probarla?
––Desde luego que no ––respond con brusquedad––. Mi organismo an no se ha recuperado de la campaa de Afganistn y no puedo permitirme someterlo a ms presiones.
Mi vehemencia le hizo sonrer.
––Tal vez tenga razn, Watson ––dijo––. Supongo que su efecto fsico es malo. Sin embargo, la encuentro tan trascendentalmente estimulante y esclarecedora para la mente que ese efecto secundario tiene poca importancia.
––Pero piense en ello! ––dije yo con ardor––. Calcule lo que le cuesta! Es posible que, como usted dice, le estimule y aclare el cerebro, pero se trata de un proceso patolgico y morboso, que va alterando cada vez ms los tejidos y puede acabar dejndole con debilidad permanente. Y adems, ya sabe qu mala reaccin le provoca. La verdad es que la ganancia no compensa la inversin. Por qu tiene que arriesgarse, por un simple placer momentneo, a perder esas grandes facultades de las que ha sido dotado? Recuerde que no le hablo slo de camarada a camarada, sino como mdico a una persona de cuya condicin fsica es, en cierto modo, responsable.
No pareci ofendido. Por el contrario, junt las puntas de los dedos y apoy los codos en los brazos de la butaca, como si disfrutara con la conversacin.
––Mi mente ––dijo–– se rebela contra el estancamiento. Deme problemas, deme trabajo, deme el criptograma ms abstruso o el anlisis ms intrincado, y me sentir en mi ambiente. Entonces podr prescindir de estmulos artificiales. Pero me horroriza la aburrida rutina de la existencia. Tengo ansias de exaltacin mental. Por eso eleg mi profesin, o, mejor dicho, la invent, puesto que soy el nico del mundo.
––El nico investigador particular? ––dije yo, alzando las cejas.
––El nico investigador particular con consulta ––replic––. En el campo de la investigacin, soy el ltimo y el ms alto tribunal de apelacin. Cada vez que Gregson, o Lestrade, o Athelney Jones se encuentran desorientados (que, por cierto, es su estado normal), me plantean a m el asunto. Yo examino los datos en calidad de experto y emito una opinin de especialista.
En estos casos no reclamo ningn crdito. Mi nombre no aparece en los peridicos. Mi mayor recompensa es el trabajo mismo, el placer de encontrar un campo al que aplicar mis facultades. Pero usted ya ha tenido ocasin de observar mis mtodos de trabajo en el caso de Jefferson Hope.
––Es verdad ––dije cordialmente––. Nada me ha impresionado tanto en toda mi vida. Hasta lo he recogido en un pequeo folleto, con el ttulo algo fantstico de Estudio en escarlata.
Holmes mene la cabeza con aire triste.
––Lo mir por encima ––dijo––. Sinceramente, no puedo felicitarle por ello. La investigacin es, o debera ser, una ciencia exacta, y se la debe tratar del mismo modo fro y sin emocin. Usted ha intentado darle un matiz romntico, con lo que se obtiene el mismo efecto que si se insertara una historia de amor o una fuga de enamorados en el quinto postulado de Euclides.
––Pero es que lo romntico estaba ah ––repliqu––. Yo no poda alterar los hechos.
––Algunos hechos hay que suprimirlos o, al menos, hay que mantener un cierto sentido de la proporcin al tratarlos. El nico aspecto del caso que mereca ser mencionado era el curioso razonamiento analtico, de los efectos a las causas, que me permiti desentraarlo.
Me molest aquella crtica de una obra que haba sido concebida expresamente para agradarle. Confieso tambin que me irrit el egosmo con el que pareca exigir que hasta la ltima frase de mi folleto estuviera dedicada a sus actividades personales. Ms de una vez, durante los aos que llevaba viviendo con l en Baker Street, haba observado que bajo los modales tranquilos y didcticos de mi compaero se ocultaba un cierto grado de vanidad. Sin embargo, no hice ningn comentario y me qued sentado, cuidando de mi pierna herida. Una bala de jezad la haba atravesado tiempo atrs y, aunque no me impeda caminar, me dola insistentemente cada vez que el tiempo cambiaba.
––ltimamente, he extendido mis actividades al Continente ––dijo Holmes al cabo de un rato, mientras llenaba su vieja pipa de raz de brezo––. La semana pasada me consult Francois le Villard, que, como probablemente sabr, ha saltado recientemente a la primera fila de los investigadores ses. Posee toda la rpida intuicin de los celtas, pero le falta la amplia gama de conocimientos exactos que son imprescindibles para desarrollar los aspectos ms elevados de su arte. Se trataba de un caso relacionado con un testamento, y presentaba algunos detalles interesantes. Pude indicarle dos casos similares, uno en Riga en 1857 y otro en Saint Louis en 1871, que le sugirieron la solucin correcta. Y esta maana he recibido carta suya, agradecindome mi ayuda.
Mientras hablaba me pas una hoja arrugada de papel de carta extranjero. Ech un vistazo por encima y capt una profusin de signos de iracin, con ocasionales magnifiques, coups de matre y tours de force repartidos por aqu y por all, que daban testimonio de la ferviente iracin del francs.
––Le habla como un discpulo a su maestro ––dije. ––Bah!, le concede demasiado valor a mi ayuda ––dijo Sherlock Holmes sin darle importancia––. l mismo tiene unas dotes considerables. Posee dos de las tres facultades necesarias para el detective ideal: la capacidad de observacin y la de deduccin. Slo le faltan conocimientos, y eso se puede adquirir con el tiempo. Ahora est traduciendo mis obras al francs.
––Sus obras?
––Ah!, no lo saba? ––exclam, echndose a rer––. Pues s, soy culpable de varias monografas. Todas ellas sobre temas tcnicos. Aqu, por ejemplo, tengo una: Sobre las diferencias entre las cenizas de los diversos tabacos. En ella cito ciento cuarenta clases de cigarros, cigarrillos y tabacos de pipa, con lminas en color que ilustran las diferencias entre sus cenizas. Es un detalle que surge constantemente en los procesos criminales, y que a veces tiene una importancia suprema como pista. Si, por ejemplo, podemos asegurar sin lugar a dudas que el autor de un crimen fue un individuo que fumaba lunkah indio, est claro que el campo de bsqueda se estrecha mucho. Para el ojo experto, existe tanta diferencia entre la ceniza negra de un Trichinopoly y la ceniza blanca y esponjosa de un ojo de perdiz como entre una lechuga y una patata.
––Tiene usted un talento extraordinario para las minucias ––coment.
––S apreciar su importancia. Aqu tiene mi monografa sobre las huellas de pisadas, con algunos comentarios acerca del empleo de escayola para conservar las impresiones. Y aqu hay una curiosa obrita sobre la influencia de los oficios en la forma de las manos, con litografas de manos de pizarreros, marineros, cortadores de corcho, cajistas de imprenta, tejedores y talladores de diamantes. Es un tema de gran importancia prctica para el detective cientfico, sobre todo en casos de cadveres no identificados, y tambin para averiguar el historial de los delincuentes. Pero le estoy aburriendo con mis aficiones.
––Nada de eso ––respond con vehemencia––. Me interesa mucho, y ms habiendo tenido la oportunidad de observar cmo lo aplica a la prctica. Pero hace un momento hablaba usted de observacin y deduccin. Supongo que, en cierto modo, la una lleva implcita la otra.
––Ni mucho menos ––respondi, arrellanndose cmodamente en su butaca y emitiendo con su pipa espesas volutas azuladas––. Por ejemplo, la observacin me indica que esta maana ha estado usted en la oficina de Correos de Wigmore Street, y gracias a la deduccin se que all puso un telegrama.
––Exacto! ––dije yo––. Ha acertado en las dos cosas. Pero confieso que no entiendo cmo ha llegado a saberlo. Fue un impulso sbito que tuve, y no se lo he comentado a nadie.
––Es la sencillez misma ––dijo l, rindose por lo bajo de mi sorpresa––. Tan ridculamente sencillo que sobra toda explicacin. Aun as, puede servirnos para definir los lmites de la observacin y la deduccin. La observacin me dice que lleva usted un pegotito rojizo pegado al borde de la suela. Justo delante de la oficina de Correos de Wigmore Street han levantado el pavimento y han esparcido algo de tierra, de tal modo que resulta difcil no pisarla al entrar. La tierra tiene ese peculiar tono rojizo que, por lo que yo s, no se encuentra en ninguna otra parte del barrio. Hasta aqu llega la observacin. Lo dems es deduccin.
––Y cmo dedujo lo del telegrama?
––Pues, para empezar, saba que no haba escrito una carta, porque estuve sentado frente a usted toda la maana. Adems, su escritorio est abierto y veo que tiene usted un pliego de sellos y un grueso fajo de tarjetas postales. As pues, a qu iba a entrar en la oficina de Correos si no era para enviar un telegrama? Una vez eliminadas todas las dems posibilidades, la nica que queda tiene que ser la verdadera. |
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