Eliminating the impossible: This is probably the most famous of Sherlockian quotations.  It appears in six different adventures in slightly different format: Eliminate all other factors, and the one which remains must be the  truth. How often have I said to you that when you have eliminated the impossible, whatever remains, however improbable, must be the truth? It is an old maxim of mine that when you have excluded the impossible, whatever remains, however improbable, must be the truth. When you have eliminated all which is impossible, then whatever remains, however improbable, must be the truth. We must fall back upon the old axiom that when all other contingencies fail, whatever remains, however improbable, must be the truth. It is impossible as I state it, and therefore I must in some respect have stated it wrong. Improbable as it is, all other explanations are more improbable  still.

It is a capital mistake to theorize before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. It is a capital mistake to theorize in advance of the facts. It is a capital mistake to theorize before you have all the evidence.  It biases the judgment.

You know my method. It is founded upon the observation of trifles. I am an omnivorous reader with a strangely retentive memory for trifles. I have no time for trifles. It is, of course, a trifle, but there is nothing so important as trifles.

At present I am, as you know, fairly busy, but I propose to devote my declining years to the composition of a textbook which shall focus the whole art of detection into one volume.

I have investigated many crimes, but I have never yet seen one which was committed by a flying creature.

I understand, however, from the inquest that there were some objects which you failed to overlook.

Have you tried to drive a harpoon through a body?  No?  Tut, tut, my dear sir, you must really pay attention to these details.

One should always look for a possible alternative and provide against it.  It is the first rule of criminal investigation.

Here is my lens.  You know my methods.

One the contrary, Watson, you can see everything.  You fail, however, to reason from what you see.  You are too timid in drawing your inferences.

Singularity is almost invariably a clue.  The more and featureless and commonplace a crime is, the more difficult it is to bring it home.

Circumstantial evidence is a very tricky thing.  It may seem to point very straight to one thing, but if you shift your own point of view a little, you may find it pointing in an equally uncompromising manner to something entirely different.

There is nothing more deceptive than an obvious fact.

I should prefer that you do not mention my name at all in connection with the case, as I choose to be only associated with those crimes which present some difficulty in their solution.

We approached the case, you remember, with an absolutely blank mind, which is always an advantage.  We had formed no theories.  We were simply there to observe and to draw inferences from our observations.

There is no part of the body which varies so much as the human  ear.

There is nothing so unnatural as the commonplace.

It has long been an axiom of mine that the little things are infinitely the most important.

Never trust to general impressions, my boy, but concentrate yourself upon details.  My first glance is always at a woman's sleeve.  In a man, it is perhaps better to take the knee of the trouser.

Crime is common. Logic is rare.  Therefore it is upon the logic rather than upon the crime that you should dwell.

What do the public, the great unobservant public, who could hardly tell a weaver by his tooth or a compositor by his left thumb, care about the finer shades of analysis and deduction!

Always look at the hands first, Watson.  Then cuffs, trouser-knees, and boots.

There I was stretched, when you, my dear Watson, and all your following were investigating in the most sympathetic and inefficient manner the circumstances of my death.  At last, when you had formed your inevitable and totally eroneous conclusions, you departed for the hotel, and I was left alone.

It would be difficult to name any articles which afford a finer field for inference than a pair of glasses, especially so remarkable a pair as these.

There is nothing more stimulating than a case where everything goes against you.

The world is full of obvious things which nobody by any chance  ever observes.

We balance probabilities and choose the most likely.  It is the  scientific use of the imagination.

The most difficult crime to track is the one which is purposeless.

Circumstantial evidence is occassionally very convincing, as when you find a trout in the milk, to quote Thoreau's example.

The more bizarre a thing is the less mysterious it proves to be.  It is your commonplace, featureless crimes which are really puzzling, just as a commplace face is the most difficult to identify.

It is of the highest importance in the art of detection to be able to recognize out of a number of facts which are incidental and which vital. Otherwise your energy and attention must be dissipated instead of being concentrated.

You may not be aware that the deduction of a man's age from his writing is one which has been brought to considerable accuracy by experts.  In normal cases one can place a man in his true decade with tolerable confidence.

It is true that though in your mission you have missed everything of importance,  yet even those things which have obtruded themselves upon your notice give rise to serious thought.

You see, but you do not observe.

Detection is, or ought to be, an exact science and should be treated in the same cold and unemotional manner.

I never make exceptions.  An exception disproves the  rule.

I never guess.  It is a shocking habit -- destructive to the logical faculty.

Inspector Gregory, to whom the case has been committed, is an extremely competent officer.  Were he but gifted with imagination he might rise to great heights in his profession.

One true inference invariably suggests others.

By a man's finger-nails, by his coat-sleeve, by his boots, by his trouser-knees, by the callosities of his forefinger and thumb, by his expression, by his shirt-cuff  -  By each of these things a man's calling is plainly revealed.  That all united should fail to enlighten the competent inquirer in any case is almost inconceivable.

There is a strong family resemblance about misdeeds, and if you have all the details of a thousand at your finger ends, it is odd if you can't unravel the thousand and first.

Now, in my opinion, Dupin was a very inferior fellow.  That trick of his of breaking in on his friends' thoughts with an apropos remark after a quarter of an hour's silence is really very showy and superficial.  He had some analytical genius, no doubt;  but he was by no means such a phenomenon as Poe appeared to imagine.

It is a mistake to confound strangeness with mystery.  The most commonplace crime is often the most mysterious,  because it presents no new or special features from which deductions may be drawn.

When a fact appears to be opposed to a long train of deductions,  it invariably proves to be capable of bearing some other interpretation.

Lecoq was a miserable bungler.  He had only one thing to recommend him, and that was his energy.  That book made me positively ill.  The question was how to identify and unknown prisoner.  I could have done it in twenty-four hours. Lecoq took six months or so.  It might be made a textbook for detectives to teach them what to avoid.

If a herd of buffaloes had passed along,  there could not be a greater mess.

With two such men as yourself and Lestrade upon the ground,  there will not be much for a third party to find out.

There is nothing like first-hand evidence.

In solving a problem of this sort,  the grand thing is to be able to reason backwards.  That is a very useful accomplishment, and a very easy one,  but people do not practise it much.  In the everyday affairs of life it is more useful to reason forward, and so the other comes to be neglected.  There are fifty who can reason synthetically for one who can reason analytically.

There is no branch of detective science which is so important and so much neglected as the art of tracing footsteps.

We must look for consistency.  Where there is want of it we must suspect deception.

The faculty of deduction is certainly contagious.

Where a crime is coolly premeditated, then the means of coverting it are coolly premeditated also.

There are many ciphers which I would read as easily as I do the apocrypha of the agony column;  such crude devices amuse the intelligence without fatiguing it.

There are no better instruments than discharged servants with a grievance, and I was lucky enough to find one

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