The Three-Key Trimodular Block in Schubert and Brahms' Sonata Expositions

Graham G. Hunt, University of Texas at Arlington

Sonata-form expositions typically articulate two key areas, with the secondary theme, and the second key area, often announced by what Hepokoski and Darcy (1997, 2006) define as a "medial caesura" (MC). A specialized form arises when two medial caesurae appear in the middle of the exposition: the "trimodular block" (TMB). More unusual still are expositions in which these two medial caesurae articulate three key areas, a form I will call the "three-key trimodular block." Franz Schubert utilized this form in several of his sonata-form expositions, and, as James Webster (1977 and 1978) suggests, appears to have influenced Johannes Brahms, who also adopted this unusual phenomenon in some of his early and late compositions. Hepokoski and Darcy's trimodular block idea allows us to critically re-appraise this unusual form (previously discussed as the "three-key exposition" in Schachter 1983, Beach 1994, Graybill 1988 and Kessler 2006) by exploring the pieces' interactions with generic conventions (i.e., compared to traditional two-key expositions employing trimodular blocks and three-key continuous or single-MC expositions). This paper will explore the three-key trimodular block form in works by Schubert and Brahms, as well as the rare 18th-century examples of this form in Mozart, Beethoven, and Cherubini. The tonal structure of the pieces will also be considered in conjunction with the trimodular block. Hepokoski and Darcy's landmark publication Elements of Sonata Theory briefly mentions this formal phenomenon but leaves the subject tantalizingly open to further study, which this paper will undertake.