Allegro in G major for piano duet, K.357

There is a general incredulity among commentators that the unfinished Sonata in G major, K.357, can be as late as the date Köchel gives to it, which is late summer 1786. Certainly, looking at the relationship between the two pairs of hands and the b revity of the development, this Allegro seems to have more in common with the Salzburg sonatas than the F major Sonata, K.497, of the same year. The peculiarity of this movement, however, is its monothematic construction, perhaps as a result of the Haydn influence to which Mozart was particularly vulnerab le in the mid-1780s. The main theme, a very characteristic Mozart motif, is present at every level in the texture and in various keys at most points of the movement, with the strange exception of the development section.