Clearly they reflected the thoughts which possessed him， butwhether the music aided those thoughts， or whether the playingwas simply the result of a whim or fancy， was more than I coulddetermine. I might have rebelled against these exasperating soloshad it not been that he usually terminated them by playing inquick succession a whole series of my favourite airs as a slightcompensation for the trial upon my patience.
During the first week or so we had no callers， and I had begun tothink that my companion was as friendless a man as I was myself.
Presently， however， I found that he had many acquaintances， andthose in the most different classes of society. There was one littlesallow， rat-faced， dark-eyed fellow， who was introduced to me asMr. Lestrade， and who came three or four times in a single week.
One morning a young girl called， fashionably dressed， and stayedfor half an hour or more. The same afternoon brought a grayheaded，seedy visitor， looking like a Jew peddler， who appearedto me to be much excited， and who was closely followed by aslipshod elderly woman. On another occasion an old whitehairedgentleman had an interview with my companion； and onanother， a railway porter in his velveteen uniform. When any ofthese nonde individuals put in an appearance， SherlockHolmes used to beg for the use of the sitting-room， and I wouldretire to my bedroom. He always apologized to me for puttingme to this inconvenience. “I have to use this room as a place ofbusiness，” he said， “and these people are my clients.” Again I hadan opportunity of asking him a point-blank question， and againmy delicacy prevented me from forcing another man to confide inme. I imagined at the time that he had some strong reason for notalluding to it， but he soon dispelled the idea by coming round tothe subject of his own accord.
It was upon the 4th of March， as I have good reason toremember， that I rose somewhat earlier than usual， and found thatSherlock Holmes had not yet finished his breakfast. The landladyhad become so accustomed to my late habits that my place had notbeen laid nor my coffee prepared. With the unreasonable petulanceof mankind I rang the bell and gave a curt intimation that I wasready. Then I picked up a magazine from the table and attemptedto while away the time with it， while my companion munchedsilently at his toast. One of the articles had a pencil mark at theheading， and I naturally began to run my eye through it.
Its somewhat ambitious title was “The Book of Life，” and itattempted to show how much an observant man might learn byan accurate and systematic examination of all that came in hisway. It struck me as being a remarkable mixture of shrewdnessand of absurdity. The reasoning was close and intense， but thedeductions appeared to me to be far fetched and exaggerated. Thewriter claimed by a momentary expression， a twitch of a muscleor a glance of an eye， to fathom a man’s inmost thoughts. Deceit，according to him， was an impossibility in the case of one trainedto observation and analysis. His conclusions were as infallibleas so many propositions of Euclid. So startling would his resultsappear to the uninitiated that until they learned the processes bywhich he had arrived at them they might well consider him as anecromancer.
“From a drop of water，” said the writer， “a logician could inferthe possibility of an Atlantic or a Niagara without having seen orheard of one or the other. So all life is a great chain， the nature ofwhich is known whenever we are shown a single link of it. Like allother arts， the Science of Deduction and Analysis is one which canonly be acquired by long and patient study， nor is life long enoughto allow any mortal to attain the highest possible perfection in it.
Before turning to those moral and mental aspects of the matterwhich present the greatest difficulties， let the enquirer beginby mastering more elementary problems. Let him， on meetinga fellow-mortal， learn at a glance to distinguish the historyof the man， and the trade or profession to which he belongs.
Puerile as such an exercise may seem， it sharpens the facultiesof observation， and teaches one where to look and what to lookfor. By a man’s finger-nails， by his coat-sleeve， by his boot， by histrouser-knees， by the callosities of his forefinger and thumb， byhis expression， by his shirt-cuffs—by each of these things a man’scalling is plainly revealed. That all united should fail to enlightenthe competent inquirer in any case is almost inconceivable.”
“What ineffable twaddle！” I cried， slapping the magazine downon the table； “I never read such rubbish in my life.”
“What is it？” asked Sherlock Holmes.
“Why， this article，” I said， pointing at it with my eggspoon asI sat down to my breakfast. “I see that you have read it since youhave marked it. I don’t deny that it is smartly written. It irritatesme， though. It is evidently the theory of some armchair loungerwho evolves all these neat little paradoxes in the seclusion of hisown study. It is not practical. I should like to see him clappeddown in a third-class carriage on the Underground， and asked togive the trades of all his fellow-travellers. I would lay a thousandto one against him.”
“You would lose your money，” Holmes remarked calmly. “As forthe article， I wrote it myself.”
“You！”
“Yes； I have a turn both for observation and for deduction. Thetheories which I have expressed there， and which appear to you tobe so chimerical， are really extremely practical—so practical that Idepend upon them for my bread and cheese.”