The creator of the immortal Sherlock Holmes, the most celebrated detective in the history of literature, so often adapted to cinema, television and radio, British Arthur Conan Doyle (1859-1930), was a doctor. He graduated from the University of Edinburgh, and later specialised in Ophthalmology. Conan Doyle's scientific background and medical knowledge are inseparable from the way he created his stories and from the personality and modus operandi of his character.

One of the distinguishing characteristics of Conan Doyle's fiction is the way in which, without departing from fantasy and speculation, he attributes to his character the attributes of a true scientist through methods of criminal investigation and detailed descriptions of each case, since the initial stages to the surprising outcome. It is also no accident that Holmes' adventures are reported to us by a physician, the no less famous Dr John H. Watson, probably inspired by one of Doyle's colleagues, named James Watson.

Conan Doyle wrote, regarding the creation of Holmes: "... in later life I tried to build up a scientific detective who solved cases on his own merits and not through the folly of the criminal".

A peculiar feature of Sherlock Holmes is that he was cocaine addicted. This fact, not strange to the context of the time, had the strong opposition of doctor Watson. One of the most famous adaptations to television, with Jeremy Brett in the role of Sherlock Holmes, portrayed precisely this characteristic, in a remarkable scene, which is always worth revisiting: