Sonata Form, emphaisis on recognizable themes

Mozart Piano Sonata in C major, K. 545 - first movement.

Exposition mm 1 - 28

Theme 1 - mm. 1-12 C major (I)
transition - mm. 13
Theme 2 - 14-25 G major (V)
codetta - mm. 26-28

Development mm. 29 - 41 (mostly in the key of v, g minor)

Recapitulation: mm. 42 - 73
Theme 1 - mm. 42 - 56 F major - cadences in F major
transition - mm. 58
Theme 2 - mm. 59 - 70 C major
coda - mm. 71-73

Mozart's Piano Sonata in C is a very straightforward example of Sonata form. The exposition is played through twice, which makes it actually a double exposition because of the repeat sign in bar 28. This brief codetta cadences in G major, or V which is typical of the conclusion of the exposition. This leaves the listener not entirely satisfied with the cadence, which leads very well into the development section.

Interestingly during the development, Mozart begins by playing with the arpeggiated motive used in the previous codetta. Later in the development, starting around measure 35 though, the scalar 16th notes may also be traced back to the scalar passages at the end of the exposition Theme 1. Interestingly, mozart uses these scales as a method for modulation throughout by altering individual notes. His Exposition Theme 1 begins in C major, ends in G major, the development begins in G minor, ends in F major (start of recapitulation), and also the recapitulation starts in F major and eventually finds its way back to G major and C major, all with the use of these scalar 16th notes. The key to these modulatory are the manipulation of notes like F to F#, Bb to B natural, etc. which serve as 'fi' or secondary dominants to change the quality of the scales.

The recapitulation in measure 42 brings us immediately back to the familiar Theme 1 from the exposition, however it is transposed to IV (F major). Through the use of scalar 16th notes, Mozart adds an F# in measure 55 (signifying a secondary dominant) which allows this Theme 1 to cadence in G major. From this G major, we can again alter the F#, bringing it back down to F natural in the transition to get back to the original tonic C major with the second theme in measure 59.

Overall, this example of Sonata form is quite short, with a fairly brief development section, however this is quite expected; classical music tends to emphasize stability and the recurrence of themes, while using modulatory and development sections to slightly vary the harmonic and textural structure in anticipation of another noticible theme.