How do we determine the style of a composer? For figures in the European canon, including Felix Mendelssohn Bartholdy, we typically isolate specific musical features that recur conspicuously in a series of works disseminated through performance, publication, and critical reactions. The resulting impressions of form and content then create in our imagination a distinctive, composite creature of stylefor Peter Gay, a “centaur, joining what nature, it would seem, has decreed must be kept apart”1-that, through consensus, becomes associated with the composer. Thus, Mendelssohn’s trademark elfin manner runs threadlike throughout his oeuvre, from the spinning scherzo of the B-minor Piano Quartet and capriciously sinister Heine setting Neue Liebe to the scherzo of the Octet (where an orchestra of insects and amphibians from Goethe’s Faust replaces the elves), to the Midsummer Night’s Dream Overture and incidental music (where elves once again cavort in their element), and to the lithesome scherzi of the two piano trios, to cite some examples. And Mendelssohn’s obsession with learned, Bachian counterpoint also indelibly marks the composer’s music, from the early student fugues for string quartet to the chorale and mirror inversion fugues in the overtures to St. Paul and Elijah, Preludes and Fugues op. 35, and Organ Sonatas op. 65.