Rhythmic design in Mozart's piano sonata VII K.309 and Beethoven's Op.110

In Charles Rosen’s “The Classical Style” the author comments on “two principal sources of musical energy… dissonance and sequence – the first because it demands resolution, the second because it implies continuation”.

Naturally the main discussion of sonata form is concerned with pitch and key, and rhythm often takes a second or third place. This blog puts a filter on pitch and key and looks primarily at the rhythmic play in Mozart’s Piano Sonata No.VII.  There are 14 rhythmic cells in the exposition, only four of these are used in the development and the design of the recap is nearly identical to the exposition. In terms of bar length the exposition is 58, the recapitulation 58 + 4 for the coda; the development can be taken as 28 bars (just short of half the outer sections) with 8 bars of play on figures a and b as a transition to the recap. The opening bars are subdivided into two figures (a and b) as the second is used to generate momentum, particularly in the development. Some of the rhythms are varied, always with values being shortened to propel the music forward; there is one example of a phrase in diminution (bar 45 plays on the second theme – bar 35) which links to LH /RH semiquavers leading us to expect the cadence which is humorously delayed, which is just as well as Mozart gives us a delightful syncopated rhythm in the codetta. One may also note that the transition has the most pedestrian of the rhythms which only highlights the character of the principal phrases. There are a few bars of simple rhythmic filling as one would expect, but this is very limited in its use.

Much, or all of this commentary may be very familiar to those who regularly play these sonatas, but in the world of education revisiting the familiar often helps us see where we have ourselves become lax with acquaintance. Some commentators have described the design as "text book sonata form", however one responds to that observation the rhythmic work is far from commonplace. Even within the expectations of sonata form the use of dissonance (in the sense of chords being distant from the tonic) the recapitulation provides additional and surprising tension before settling down to the tonic. Playing through the sonata and considering the rhythmic play has refreshed my thinking about composition and for this reason alone I am happy to share the observations in this blog.

Mozart's early sonata No. 7 is full of rhythmic diversity with a large number of different rhythmic cells in the exposition. These are considerably reduced in the development and reinstated, as one might expect, in the recapitulation.

it would be strange if Beethoven's approach to rhythm had not developed in the Mozart in the intervening period. Like Mozart's sonata Beethoven's exposition is full of rhythmic play, the essential difference is that each of Mozart’s rhythmic cells has its own identity while Beethoven's rhythms create the sensation of evolving from each other. One would expect the repetition of rhythms (Mozart usually repeats his twice or three times), in Beethoven’s hands these are fewer and successive phrases undergo small degrees of variation.

The opening four bars are rhythmically complex, the first pair of notes being followed by their diminution, the second phrase takes this second (shorter) rhythm and extends it with a flourish (trill and demisemiquavers). This moves the musical argument on to the “proper” start of the music, the same intention is heard again at bar 27.

The rhythm of bars 5 and 6, and their exact repetition 7 and 8 have a simpler outline with bar ten developing the pattern in the second half. Bar 6 is a repeat of bar 2 so we can hear 5 and 6 as a simplification of the opening bars.  The increased momentum of bars 9 to 11 leads to the demisemiquaver arpeggios.  Looking at the pitch structure for a moment each first beat of four demisemiquavers form octaves over 5 octaves, and the momentum is marked by a rising scale on the beat (A flat, G, A flat to A flat one octave above).

The rhythmic interest is not in the running demisemiquavers but in the left hand where the pulse is repeated twice and then developed by chords on the second and third beats.  From bar 20 the interest is in the left hand / right hand interplay of dotted quaver semiquavers figures. This gentle (legato) section has the effect of slowing the music down at the half way point of the exposition with the trills acting as a further restraint before the demisemiquaver turn of bar 27 moves on to the second half of the exposition. Bar 31 sees another close variation on the opening figure before going through an extended semiquavers passage taking us back to the development. The presence of the opening bar is also felt at bar 33 and in augmentation in the left hand at 36/37.

Several commentators have noted the simplicity of the design of the development, from the rhythmic viewpoint bars 1 and 2 form the main argument taking us from bar 40 to 55 with eight repetitions. After the first four bars (40 – 44) the left hand rhythm forms syncopated phrases from the second semiquaver beat, this has been prepared for the listener in bars 33 to 35.

56 marks the start of the recapitulation. Bar 55 has the left hand provide the demisemiquaver lift into the main argument, this time the pulse heightened with continuous 32^nd notes in the left hand while the right has 2 versions of the opening rhythm before left and right hands exchange the role. Bar 63 follows the pulse pattern of bar 5 onwards with slight variations increasing the momentum. The argument is familiar even if small changes take place, however bar 100 introduces a new rhythm with a minim tied over to a quaver, quaver minim. This interjection might be taken as a final breath before moving to the close but it may also be heard as a preparation for the much simpler rhythms of the Allegro molto.

The Mozart sonata was composed in 1777 and the Beethoven in 1821, the 44 years difference mark considerable changes in the use of key structure, tonal qualities of the piano and many other features.  The developments in rhythm are of equal interest, of course it can be argued that the rhythms of this particular Mozart sonata are notable for their “small unit” approach. It is, in my opinion, worthwhile exploring these works through a filter to reveal their structures; though our use of rhythm has evolved to explore repetition and variation in both simpler and more complex forms there is much to learn from these works about creating momentum that can be of use in music today.