According to the text of the tale, the reason for the narrator's monomaniacal obsession with the man stems from "the absolute idiosyncrasy of man's expression". He is the only person walking down the street the narrator can't categorize. Why the narrator is so haunted by him is not entirely clear, though it is implied that the two men are two sides of the same person, with the old man representing a secret side of the narrator, though the narrator is unable to see this. The old man may be wandering through the crowd in search of a lost friend or to escape the memory of a crime. The possible evil nature of the man is implied by the dagger that is possibly seen under his cloak - whatever crime he has committed condemns him to wander. This lack of disclosure has been compared to similar vague motivations in "The Cask of Amontillado". Poe purposely presents the story as a sort of mystification, inviting readers to surmise the old man's secret themselves.