Violin Sonata in F major, K.376 (1781)

One way of securing equality between solo instruments is to ensure that they share the melodic interest by alternating the material between them - which is the principle, carried out with scrupulous fairness, behind the scoring of the Sinfonia Concertante in E flat K364. In the first of the two F major Violin Sonatas in the Vienna set, written a couple of years after the Sinfonia Concertante, Mozart does not discard the principle of alternation but also explores other ways of keeping the violin and piano profiles in balance. The main theme of the first movement, presented by the piano after three introductory chords, remains the exclusive property of the keyboard instrument which, in recompense, has no share in the answer offered by the violin. The second subject begins as a piano solo but, on the entry of the violin, becomes an animated dialogue. Another second-subject melody passes from piano to violin, which latter instrument adds the closing theme of the exposition. In the short development a new theme derived from a phrase in the first subject alternates between the two and, although the material is distributed in not quite the same way as in the exposition, the recapitulation retains the balance.

There is no exclusivity in the B-flat-major Andante where lyrical melody alternates between the two instruments in tender mutuality throughout. After providing the piano with a low murmuring accompaniment to its first theme, the violin takes it up in the same key and, although in this case the harmonies change with the change of colour, much the same happens with the second theme. The principle holds good in the middle section, where the violin presents the theme in F under a sustained trill before the roles are exactly reversed.

The Rondeau is a well-sustained construction on a characteristically graceful theme, always shared between the two instruments, with two episodes, the first of which includes the one instance of minor-key drama in the whole work. There are one or two, probably accidental, references to themes from earlier movements and, before the last return of the rondo theme, a witty fermata which leads nowhere and has to be set up again with a different harmony.