The predominant mode of Maupassant’s psychological stories is not the manifestation of the ghostly supernatural in the traditional sense; rather the stories focus on some mysterious dimension of reality that exists beyond what the human senses can perceive. But even as this realm of reality is justified rationally, the reader is never quite sure whether the realm truly exists "out there" in the world of the story or whether it is a product of the obsessive mind of the narrator. The style of several of these tales is similar to some of the stories of Edgar Allan Poe and Ambrose Bierce, particularly the stories of the perverse which combine narrative story line with the narrator's quasi-philosophic considerations of madness, murder, and the mysterious realm beyond the pale of ordinary understanding.
The most explicit story to focus on this realm, parts of which are used later in the more famous La Horla, is "Letter from a Madman." As told by the narrator to a doctor, the story unfolds a theory that the human mind receives only sparse and uncertain information about the external world because the limitations of the five senses restrict what humans can perceive. The narrator argues, for example, that if we had additional senses we could perceive a reality that is closed to our present senses. From this assumption he tries to infer, rather than directly perceive, the mysterious