J. HAYDN: String Quartet in C major, Op. 20 No. 2, Hob. III:32
W. A. MOZART: Piano Quartet in G minor, K. 478
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W. A. MOZART: Sonata for Fortepiano and Violin in D major, K. 306
L. van BEETHOVEN: Piano Quartet in E-flat major, Op. 16a

Haydn’s six string quartets, Op. 20, composed in 1772—which we refer to as the “Sun Quartets” series, following the title page of the Berlin edition—mark a turning point in the history of the genre. Here, the four instruments are no longer the first violin and its accompanying ensemble, but rather a group of equal parts. The Quartet in C major illustrates this particularly well: the theme of its opening movement is introduced by the cello, and its finale is a four-part fugue. Mozart followed this model and perhaps took on an even greater challenge when he elevated the piano beyond its usual role as an accompaniment instrument. With his dramatic Piano Quartet in G minor, he secured a lasting place for this still relatively young genre, while in his Violin Sonata in D major—the closing piece of the Parisian “Palatinus” sonatas—he created a lively dialogue within a much more intimate setting. Between Beethoven’s piano quartet and its original quintet version, written for wind instruments, it is the piano itself that serves as the link: while the piano part remains unchanged, the material unfolding around it takes on varied hues.