Analyse Mozart's treatment of the Theme and Variation for in the first movement of K331.

The second variation also uses many of the same contents of the theme, including (as above) metre, key, cadences etc.. The pedal note is also present in this variation, although a little less obvious. The triplet rhythm in the left hand always ends on the pedal E (Fig 3), as in the theme. Also used is the same sequence of notes in the right hand rhythm as in the theme (Fig 3). Mozart also decorates this variation with trills or acciacceturas in nearly every bar. In the second phrase, the pedal note disappears from the left hand as with the triplet rhythm, but is still present, only played by the right hand. In the third phrase, the pedal note returns to the left hand and Mozart continues the pattern of ornaments in the right hand.

The third variation introduces a change in key, from major A, to the tonic minor, although as before, the metre, harmonies and cadences etc. are the same. In this variation, Mozart changes the texture of the music to polyphonic texture from homophonic as it was before. Mozart also introduces a piano technique known as the Alberti Bass (named after Domencio Alberti, its inventor), which is a feature used in some of the later variations. In this Alberti Bass, the pedal note is still apparent in the broken chord form. Mozart also uses the piano technique of using octaves in the right hand (Fig 4).

In the fourth variation, the key resolves in the tonic major, where it stays for the remainder of the movement. As with all the preceding variation, the metre, form etc. are still the same. Mozart changes ‘instrumental style’ from the previous variation, where he used techniques typical of the piano in the octave leaps in the right hand. This time, Mozart used a typical harpsichord technique in the crossing of the hands, where the highest notes in the left hand are a relic of what is being played in the right hand. In this variation, the pedal note seems to have been lost, but in fact, it has been moved into the right hand in the first phrase, but reverts back to the left hand in the Alberti bass in the second phrase. Some of the dynamics of the theme are used in the third phrase of this variation, in nearly the same places as the theme. They fall in the third bar, as the first and second notes are played sforzando as in the theme. The fourth and final phrase of this variation is a mimic of the first phrase with the hand crossing and the right hand pedal note.

The fifth variation, the Adagio variation, the metre, key, cadences etc. stay the same, but as the direction suggests, the tempo changes to twice as slow. This was typical of Mozart in all of his theme and variations pieces, that the penultimate variation was to be slower that its precursors. In the left hand stays in the same style as the previous variation, with the Alberti bass and pedal note in the first phrase, but the second phrase is more of a variation on the first variation with the repeated notes in the left hand which occur in the first variation. This variation also uses a vast array of grace notes, especially towards the cadences. Also new in this variation is the use of first and second time repeats, which have not been uses elsewhere in the piece.

The finale variation returns to an allegro tempo, with all the same other features as mentioned before, such as the metre, key and cadence etc. In the first phrase, the pedal note is still present in the broken chord Alberti bass in the left hand, but in the second phrase, the left hand changes to a series of arpeggios of the tonic (amongst others) chord. The same is said for the structure of the third phrase. As in the Adagio variation, first and second time repeats are used, but in this final movement, there is an eight bar ‘coda’ which acts as a summing up of the entire movement, using all the features of the previous variations and the theme, ending as usual on the tonic chord.