Movement to a Piano Sonata for Two Pianos in B♭, K. 375c
di Wolfgang Amadeus Mozart
Mozart’s Movement to a Piano Sonata for Two Pianos in B♭ major (K. 375c) is a short surviving fragment from Vienna in 1782, when the 26-year-old composer was consolidating his new freelance life in the imperial capital. Preserved as a single sonata movement, it gives a tantalizing glimpse of Mozart thinking in the bright, public-facing idiom of the two-keyboard sonata.
Background and Context
Mozart wrote the fragment K. 375c in Vienna in 1782, at a moment when he was freshly established outside Salzburg’s court system and investing heavily in keyboard music—both as a performer-composer and as a teacher for the city’s cultivated amateurs. The piece survives as a single movement for two pianos, and modern editions treat it as an incomplete sonata movement rather than part of a securely documented, multi-movement sonata. The Neue Mozart-Ausgabe prints it among the fragments for two keyboards, underscoring its unfinished status and limited source basis.[1]
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Musical Character
On the page, K. 375c reads like the opening of a Classical sonata movement—compact, energetic, and designed for dialogue between equals rather than a solo with accompaniment. The musical texture alternates between chordal declarations and nimble figurations that can be tossed from one player to the other, a two-piano “conversation” that hints at the concerto-like brilliance Mozart had already cultivated in his finished two-piano works. Only a short span of music is transmitted (the movement breaks off early), so any full formal trajectory remains conjectural; what survives is chiefly the promise of an exposition in B♭ major, with the characteristic clarity and buoyant rhythm that make this key such a natural home for Mozart’s Viennese keyboard style.[2]
[1] Digital Mozart Edition (Mozarteum): NMA IX/24/1 (2 Keyboards), table of contents listing “Sonata movement in Bb for two Keyboards (fragment) KV App. 43 (375c)”
[2] IMSLP work page: Sonata Movement in B-flat major, K.Anh.43/375c — basic catalog data (Vienna 1782; fragment; instrumentation: 2 pianos) and links to the NMA scan