Schubert's SLIDEs: Tonal (Non-)Integration of a Paradoxical Transformation

SLIDE, the transformation that exchanges triads sharing the same third, is a pervasive feature of Schubert's mature works. Blending indicators of distance and proximity, complexity and direct intelligibility, SLIDE is the chromatic progression par excellence for evoking liminal states. Schubert's use of the transformation poses a challenge to our ability to reconcile prolongational and transformational modes of tonal hearing. Following an evaluation of historical and group-theoretical conceptions of SLIDE, this article proposes a set of functional paradigms through which the relation may be understood in Romantic harmony. Extrapolating patterns of SLIDE usage from Schubert's oeuvre illuminates the procedures through which the progression may be integrated into tonal fabrics. Special attention is given to the four-hand piano duets, D. 812, 940, and 947 in particular; in these works, the presence of sonata form forces SLIDE's incorporation into exposition structures. The D. 812 Grand Duo is used as a concluding case study. To fully appreciate its complex game of semitonal relations, the Duo requires overlapping transformational narratives and a revival of Karg-Elert's idiosyncratic Terzgleicher function. In studying Schubert's SLIDing chromaticism, we stand to understand how composers ensconced within the tonal common practice nevertheless found ways to selectively incorporate tonally paradoxical materials into diatonic forms.