IF WE CONSIDER Edgar Allan Poe's “The Gold-Bug” (1843) and his three Dupin tales—“The Murders in the Rue Morgue” (1841), “The Mystery of Marie Rogêt” (1843–44), and “The Purloined Letter” (1845)—we may readily focus on Legrand and his friend versus Dupin and his friend, or the American setting versus the Parisian one. Clearly for a tale about Captain Kidd and an English-language puzzle, an American setting was necessary. And perhaps, as J. Gerald Kennedy has suggested, “The Gold-Bug” is the turning point in Edgar Allan Poe's career—that is, the point at which Poe began to focus primarily on American locales rather than foreign ones. But it may be interesting to consider formal matters—the turning point of that turning point, the midpoint, the center of “The Gold-Bug”—in relation to the centers of the Dupin tales.

Poe wrote in Eureka (1848) that “the sense of the symmetrical is the poetical essence of the Universe,” and we have already seen that symmetry is often a structuring principle of his fiction. Further evidence to be adduced here suggests that “The Gold-Bug” features the framed central chiasmus of “Rue Morgue” and “Marie Rogêt” and anticipates the framed central shift and the formally significant nearpalindrome of the coming “Purloined Letter.” In other words, “The Gold-Bug” shows Poe experimenting with form for a ratiocinative tale, drawing elements from an earlier design and working through elements of a later one, even as he always maintained his controlling symmetry.

In the case of “Rue Morgue,” symmetrical phrasing frames a chiastic center, the verbal pattern ABBA, yielding the X. Poe played with this trope in a chiastic sentence in his jeu d'esprit, “X-ing a Paragrab”: “X, everybody knew, was an unknown quantity; but in this case … there was an unknown quantity of X” (M 3:1375). If “X” is A and “unknown quantity” is B, then we have the pattern ABBA, the chiastic crisscross.