The Technique of the Mystery Story

The Detective Story as we know it was first written by Poe, yet he never used the descriptive word, nor was Dupin a detective, either professional or amateur, for when Poe wrote his immortal Dupin tales, the name "Detective" Stories had not been invented; the detective of fiction not having been as yet discovered.

The fact is, meanwhile, that, in the Riddle Story, the detective was an afterthought, or, more accurately, a deus ex machina to make the story go. The riddle had to be unriddled; and who could do it so naturally and readily as a detective? The detective, as Poe saw him, was a means to this end; and it was only afterwards that writers perceived his availability as a character. Lecoq accordingly becomes a figure in fiction, and Sherlock, while he was yet a novelty, was nearly as attractive as the complications in which he involved himself.