Sonata in C major for piano duet, K.19d

There is reason to believe that the Sonata in C major, K.19d, was written in May, 1765, when the Mozart family was in London. a cryptic notice in the Public Advertiser refers to “a concert on the harpsichord by the little composer and sister each singly and both together.” This might have something to do with the Sonata in c major, although no one has been able to explain why, in that case, it was published only years later and in Paris. Whatever the exact date - and 1765 seems early for such an assured piece of work - it must have been written before the two Salzburg sonatas, which are more mature in style and more clearly defined in form.

In the first movement of the C major Sonata there is no obvious second subject theme, although there is a modulation to the dominant at the appropirate point in the exposition, and the recapitulation by-asses the first theme of the first subject. The middle section, on the other hand, with its subtle allusions to the expositions and its modulatory freedom is quite remarkable.

The Menuett and trio are comparatively conventional, but the Rondeauy is another suprising movement, and not only because of its main theme, which Mozart used again in the Serenade in B flat, K.361, in 1780. The last episode is an Adagio which interrups the rondo theme in mid-flight and which in the course of its ruminations refers back , deliberately or not, to the theme of the Menuetto.