Poe's great story about conscience is unusual in several ways. Although Poe unjustly accused Hawthorne of having lifted passages from "William Wilson for use in Hawthorne's tale "Howe's Masquerade," Poe admired Hawthorne; "William Wilson" is, indeed, his most Hawthornian story. The moral emphasis reminds one of Hawthorne, as does the manner of making a character an emblem of a spiritual trait. Poe also used Hawthorne's favorite technique for suggesting the incredible while maintaining credibility: he made the strangest occurrences in his story ambiguous. Wilson says that he could only "with difficulty shake off the belief" that he had known his double in a prior life; often the double appears when Wilson is "madly flushed" by liquor or excitement. Readers see the double as conscience and note that Wilson sometimes welcomes the interruptions. Those facts and Wilson's hereditary imaginativeness give room to interpret the events of the tale either literally or as the creations of a guilt-ridden and diseased mind.
"William Wilson" is unusual also in that it contains a very rare and uncharacteristically "realistic" description of childhood. The only other child whom Poe developed in any detail is Arthur Gordon Pym in Poe's novel. More typical of Poe is the familiar passage about how the narrator comes from an "imaginative and easily excitable race." That passage is present, too, as a prop to credibility.
Poe achieves power through accelerated rhythm as well. After the lengthy portion of the story set at Dr. Bransby's school, subsequent scenes are successively shorter. The result is almost cinematic, like the effects filmmakers can achieve through rhythmic "cutting"; the effect is to make Wilson's later adventures whiz by dizzyingly.
An interesting ambivalence is evident here and elsewhere in Poe, who can be alternately--and sometimes simultaneously--democratic and snobbish. Wilson is shown to be arrogant and aristocratic; he is, for instance, ashamed of his "common" name and regards institutions of higher learning as playgrounds for the elite. We as readers are supposed to dislike him for his snobbery. The usually antidemocratic Poe, in other words, at times reveals strong antiaristocratic biases. (Compare "The Masque of the Red Death" and "Mellonta Tauta.")
A note of explanation: The sources of Poe's ideas in this tale have been very thoroughly studied and make an interesting story. Details are nicely summarized in Mabbott (9, II). Poe felt so much in debt to Washington Irving's 1836 article "An Unwritten Drama by Lord Byron" that he wrote to Irving to tell him about the tie. Irving's piece outlines the idea of the double as a "spectre," "an allegorical being, the personification of conscience." It in turn involves connections from Byron to Percy Bysshe Shelley and ultimately to Calderón.