One dumb-bell, Watson! Consider an athlete with one dumb-bell. Picture to yourself the unilateral development - the imminent danger of a spinal curvature. Shocking, Watson, shocking!
They say that genius is an infinite capacity for taking pains," he remarked with a smile. "It's a very bad definition, but it does apply to detective work.
Before turning to those moral and mental aspects of the matter which present the greatest difficulties, let the inquirer begin by mastering more elementary problems.
As Cuvier could correctly describe a whole animal by the contemplation of a single bone, so the observer who has thoroughly understood one link in a series of incidents should be able to accurately state all the other ones, both before and after.
...Holmes, who loathed every form of society with his whole Bohemian soul, remained in our lodgings in Baker Street, buried among his old books, and alternating from week to week between cocaine and ambition, the drowsiness of the drug, and the fierce energy of his own keen nature.
He [Professor Moriarty] is the Napoleon of crime, Watson. He is the organizer of half that is evil and of nearly all that is undetected in this great city. He is a genius, a philosopher, an abstract thinker. He has a brain of the first order.
It has always seemed to me that so long as you produce your dramatic effect, accuracy of detail matters little. I have never striven for it and I have made some bad mistakes in consequence. What matter if I hold my readers?
The ideal reasoner, he remarked, would, when he had once been shown a single fact in all its bearings, deduce from it not only all the chain of events which led up to it but also all the results which would follow from it.
So swift, silent and furtive were his movements like those of a trained bloodhound picking out a scent, that I could not but think what a terrible criminal he would have made had he turned his energy and sagacity against the law instead of exerting them in its defense. -Dr. Watson, The Sign of the Four
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
If the fresh facts come to our knowledge all fit themselves into the scheme, then our hypothesis may gradually become a solution. Sherlock Holmes speaking with Dr. Watson.