The Medial Caesura and Its Role in the Eighteenth-Century Sonata Exposition

The authors are developing a genre-based “Sonata Theory,” according to which moment-to-moment compositional choices in sonata-form works are understood as elements of an ongoing dialogue with reasonably ascertainable, flexible norms. One of the most important tonal/rhetorical features of the “two-part exposition” (i.e., an exposition with a secondary theme) c. 1800 is the medial caesura, bringing an emphatic end to Part One and simultaneously making available the “secondary-theme zone” that launches Part Two. Composers treated the medial caesura in several standard ways, but they could also subject it to generic “deformation” for structural or expressive reasons that become clearer once the norms surrounding medial-caesura activity are understood.