Violin Sonata No. 21 in E minor, K.304

The sonata has just two movements, unusual for Mozart, and both stay in the shadow of E minor rather than resolving into a bright major finale.

I. Allegro: The violin and piano state the opening idea together, in unison, a stark, unadorned melodic line rather than a tune with accompaniment. This bare, questioning opening returns throughout the movement, giving it a restless, searching character rather than the poise typical of Mozart's Paris-era works. Listen for how sparse the texture stays; there is little decoration, and the minor key colors even the lyrical second theme.

II. Tempo di menuetto: Instead of a slow movement, Mozart writes a minuet, but a somber one, its dotted rhythm walking rather than dancing. Partway through, the music shifts into E major for a gentler middle section, a moment of real warmth after the tension of the first movement. This major-key episode feels like sunlight breaking through before the minuet returns and the sonata closes quietly, still touched by minor-key melancholy.

Mozart composed this sonata in Paris in 1778, during a difficult trip on which his mother, who had traveled with him, died in July of that year. It is one of a set of violin sonatas he wrote or revised for publication in Paris, issued there as part of a collection dedicated to the Electress of the Palatinate. Of all Mozart's violin sonatas, it is the only one in a minor key, and listeners and scholars have long connected its unusually somber tone to the loss he experienced while writing it, though Mozart left no direct comment linking the two. The sonata was published in 1778 and has remained a favorite recital piece for its concentrated expression and modest scale, requiring no elaborate forces, only violin and piano.