Arthur Conan Doyle, creator of Sherlock Holmes, freely acknowledged his deep indebtedness to Edgar Allan Poe, whose tales of ratiocination featuring the amateur detective C. Auguste Dupin, were so well conceived, Doyle said, that nothing could be done to improve upon the conventions they established. In the opening paragraph of "The Murders in the Rue Morgue" Poe describes the possessor of a keen analytical mind in terms that would characterize literature's most famous detective, Sherlock Holmes.
THE MENTAL FEATURES discoursed of as the analytical, are, in themselves, but little susceptible of analysis. We appreciate them only in their effects. We know of them, among other things, that they are always to their possessor, when inordinately possessed, a source of the liveliest enjoyment. As the strong man exults in his physical ability, delighting in such exercises as call his muscles into action, so glories the analyst in that moral activity which disentangles. He derives pleasure from even the most trivial occupations bringing his talents into play. He is fond of enigmas, of conundrums, of hieroglyphics; exhibiting in his solutions of each a degree of acumen which appears to the ordinary apprehension preternatural. His results, brought about by the very soul and essence of method, have, in truth, the whole air of intuition.
Like Poe's amateur detective C. Auguste Dupin, Doyle's Sherlock Holmes "derives pleasure from even the most trivial occupations bringing his talents into play." This is the case in "The Adventure of the Red-Headed League," a story in which Holmes becomes involved with the comical Jabez Wilson, who hopes to get the famous detective to help him recover his job copying articles out of the Encyclopedia Britannica without charging him for his services. Wilson is gratified when Holmes agrees to take on the case, not realizing that Holmes has almost immediately detected much deeper significance to the problem than either Wilson or Dr. Watson could imagine.
Sherlock Holmes is constantly complaining that he needs problems to solve. His brain is always working, but it needs puzzles to analyze. His hyperactive brain is represented in his tall, ascetic physique and hawklike features, and it is responsible for his restlessness and bursts of energy, as well as for his quick, precise speech. He will spend hours examining an old hat, as he does in "The Adventure of the Blue Carbuncle," or creating a mental picture of the owner of an old walking stick, as he does in the opening of "The Hound of the Baskervilles."
What was important to Doyle was that his hero's interest in solving problems would enable the author to create stories involving all types of characters from the most humble to the most exalted, and all types of puzzles from the most trivial to problems involving fortunes in gold and issues threatening the balance of powers in Europe.
Holmes calls himself a "consulting detective." Today we would call him a "private eye." Most private detectives work for people who can afford to pay their fees and expenses, but Holmes has a broader spectrum of clients and mysteries because he will only accept cases that challenge his brilliant analytical mind. Why should he take on a case that could be solved by a mediocre police detective like Inspector Lestrade? Holmes can also be motivated to help ladies in distress, innocent men wrongfully accused of serious crimes and threatened with disgrace, years in prison, and sometimes execution, and in some tales motivated by patriotism when a case involves an issue of vital importance to the British government. Because Holmes sometimes receives enormous rewards from rich and prominent clients, he can live in comfort and devote most of his time to analyzing any problem that intrigues him, no matter how seemingly petty or arcane. This must explain what Poe meant about his own analytical genius C. Auguste Dupin when he opened "The Murders in the Rue Morgue" with the epigraph from "Urn Burial" by Sir Thomas Browne:
What song the Syrens sang, or what name Achilles assumed when he hid himself among women, although puzzling questions are not beyond all conjecture.