the complete works for four hands at one and two pianos

A portrait of the Mozart family painted by Johann de la Croce in 1780 shows the 24-year-old composer and his sister sitting together at the keyboard, Wolfgang at the bass and Nannerl at the treble, his right hand crossing her left in a characteristic piano-duet manoeuvre. At that time four hands at one piano were still a family affair. A year later, when Mozart wanted to write something more sensation for himself and a star pupil to play in public, he wrote the Sonata for two pianos, K.448.

According to a letter which Nannerl wrote to the publishers Breitkopf and Härtel, Mozart had been writing piano duets since the age of four. The earliest surviving example, however, is the Sonata in C, K.19d, which was apparently written in London in 1765. If that date is right his concept of the piano-duet sonata changed little in the seven years between then and 1772, when he wrote the first of his two Salzburg sonatas (in D major, K.381). Like its companion (in B flat major, K.358) written two years later, it is delightfully intimate music but structurally and expressively unenterprising.

It was not until 1786, after a promising attempt in the unfinished Sonata in G major, K.357, that he gave four hands at one piano a work of the size which between them they can undoubtedly carry. Obviously in a medium where the pianists have to keep so precisely together that, except where long-practised experts are concerned, rhythms become inflexibly rigid and the performance seems mechanical, there are obstacles for an ambitious composer. However, in the Sonata in F major, K.497¹, Mozart solved the problem by making a virtue of that same piano-duet characteristic. The strength of the work derives from its persistent regularity sustained, at least in the outer movement, through expanded strcutres. It is a fascinating anticipation of Schubert’s work in the same medium. The Sonata in C major, K.521, written in the following year, marries the regularity with keyboard brilliance, giving the duet sonata the kind of quality which Mozart evidently felt was lacking in 1781.

Another advantage of piano-duet regularity is that it is the ideal medium - better than the original, though obviously unauthentic - for presenting the very remarkable music which, towards the end of his life, Mozart wrote for the detested mechanical organ. In these transcription, though they are not by Mozart himself, Ariel is set free from his cloven piano.

1see Solomon (p312) who thinks it was written for the Jacquins