The article is a comparative investigation of sonata-form literary narratives employing William H. Gass's "Cartesian Sonata" and Leo Tolstoy's The Kreutzer Sonata as a joint sample case. Sonata properties are revealed in the two novellas' contents, not form, by way of linking them with the nineteenth-century "gendered" explanation of the sonata layout. Intermedial relations between sonata phenomena in fiction and music are regarded to be intertextual. The "sonata" status of the Gass novella is acquired when the author combines three previously published fragments under a "musicalized paratext," providing no musical clues beyond the title. Decrypting that title, the article focuses on the idea of sonata form, which the term's coiner A. B. Marx once described as a relationship between "masculine" and "feminine" tonal subjects. Without musicological expertise, the intersexual conflict between Gass's characters is difficult to relate to Marx's metaphor. This relation is facilitated by pairing Gass's literary "sonata" with Tolstoy's. The tonal structure of Beethoven's "Kreutzer"—the catalyst of marital disaster in Tolstoy—is shown to share certain affective parameters with Gass's and Tolstoy's narratives. The established connections are instructive insofar as texts, contexts, and readings from different zones of cultural experience transform and enrich one another.