The most significant contribution Poe's detective stories make to the development of the short story consists of their basing a story's central theme and structure on the very process by which the reader perceives that unifying structure and pattern. They are Poe's most explicit examples of works in which questions of interpretation are not outside the story but are involved in every stage of the narrative development. Poe was self-consciously aware that he was embodying both the creator and the explicator in his so-called stories of ratiocination, for the stories are indeed about creating patterns. It is all a matter of accepting a mystery as a text, a contextual pattern made up of motifs or clues, which have meaning precisely because of the role they play within the pattern.
According to Shawn Rosenheim, Poe's detectives work with abstract symbols alone, which they obtain by converting the material world into a surface of discrete signs in which nothing is hidden. This method is also related to gothic fiction, says Rosenheim, for it transforms representations of three-dimensional space into binary codings. In this transformation of the world into an intertextual network, it is the detective, as G. K. Chesterton has one of his own characters say, who is the critic, while the criminal is the creative artist who creates the plot the detective must perceive as pattern. Truly, as Chesterton suggests, the detective is the master of the "romance of detail"; and the transformation of ordinary detail, previously mere verisimilitude, into contextually meaningful motifs is a key factor in the creation of not only the detective story but the short story as a genre.
The story which takes the credit for being the first detective story, "The Murders in the Rue Morgue" (1841), begins under the guise of an essay, much as many of Poe's other stories do, taking its generic cue from the eighteenth-century essay form characteristic of Addison and Steele. The subject of this opening essay, presented objectively by a writer who has not yet identified or dramatically located himself, is, as it is in "The Imp of the Perverse," a particular mental state. Although analysis is in some ways just the opposite of perverseness (for whereas one creates mysteries, the other resolves them), like perverseness, it is not susceptible of analysis itself. Like the perverse, the analytical faculties reveal themselves in their effects only.
There is no way to determine their cause; the process of analysis is simultaneous with its effects. Furthermore, what characterizes the analytical is that even though it is the "soul and essence of method," to the ordinary perception it appears intuitive; even though it is the result of acumen, it appears to be "preternatural." These are also key terms for understanding Poe's contribution to the short story, for, as Poe shows, although the form requires careful control and method, it results in a work with a shadow of the "mystic" or the seeming preternatural about it.
The narrator notes that he is not writing a treatise, but rather prefacing a "somewhat peculiar narrative'; however, at the point when the actual narrative begins he says the narrative to follow "will appear to the reader somewhat in the light of a commentary upon the propositions just advanced." If one asks which is primary, the narration or the exposition, the answer of course is that neither is, for when Dupin begins his own exposition and illustration of the analytical method, narrative becomes exposition.
The "re-solution" of the mystery is the presentation of the hidden narrative itself, laid bare by the "disentangling" method of the analyst. The narrator observes in Dupin what he calls the "Bi-Part Soul," seeing a "double Dupin--the creative and the resolvent." And indeed, for Poe the creative is the resolvent, for to create is to re-solve, to engage in a re-solution--the discovery of the hidden pattern which made the mystery a mystery. Dupin notes that the problem with the French police is that they often hold things up too close, and thus lose sight of the matter as a whole. Dupin's point here is that what must be perceived is indeed the overall pattern--how the objects fit together. Moreover, he notes that to stare too intently at the object directly and straight on is to make it disappear, that one must look at mysteries in a "side-long way," that is, indirectly, the way one must often look at a literary text.
Another element of the crime story that contributes to Poe's development of the short story genre is that what most confounds the police is the fact that the crime, like Poe's notion of the perverse, seems completely unmotivated. Although the lack of a motive is what makes the mystery so seemingly insoluble for the police, for Dupin, it is precisely its lack of a motive, precisely its outré features, that makes it so easy to solve. Dupin says that it is by these very deviations from the ordinary that reason feels its way toward truth.
Whereas the police are looking for precedents for the crime in the past and for some realistic or logical motive for its severity, Dupin succeeds precisely by throwing himself out of the ordinary and accepting the extraordinary nature of the event. By making the animal the source of the crime, Poe illustrates one of the key factors of the detective story--that to try to solve the mystery by postulating the usual is futile, for crime itself is a breakup of the ordinary and the everyday. The fact that there is no motive for the crime is a typical Poe device, for it forces one to abandon so-called realistic motivation and concentrate on the purely contextual or aesthetic motivation.