01_031
«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.
01_032
He is only wanting in knowledge; and that may come in time. He is now translating my small works into French.»
01_033
«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.»
01_034
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.
01_035
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.
01_036
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.»
01_037
«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.
01_038
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.
01_039
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.»
01_040
«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.»
01_041
«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.»
01_042
«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.»
01_043
«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.
01_044
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.
01_045
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.»
01_046
«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.
01_047
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.»
01_048
«In this case it certainly is so,» I replied, after a little thought. «The thing, however, is, as you say, of the simplest. Would you think me impertinent if I were to put your theories to a more severe test?»
01_049
«On the contrary,» he answered, «it would prevent me from taking a second dose of cocaine. I should be delighted to look into any problem which you might submit to me.»
01_050
«I have heard you say that it is difficult for a man to have any object in daily use without leaving the impress of his individuality upon it in such a way that a trained observer might read it. Now, I have here a watch which has recently come into my possession.
01_051
Would you have the kindness to let me have an opinion upon the character or habits of the late owner?»
01_052
I handed him over the watch with some slight feeling of amusement in my heart, for the test was, as I thought, an impossible one, and I intended it as a lesson against the somewhat dogmatic tone which he occasionally assumed.
01_053
He