Catherine's post

Beethoven’s energetic Piano Sonata in C Major begins with the very common Major I chord, but surprisingly changes to a secondary dominant. Following this secondary dominant are two measures of dominant chords. In turn, this prepares for the string mixture chords, which begin with bVII. This quickly moves into two measures that contain a string of sixteenth note chords, and moves into an unanticipated simple movement into a half cadence. The elements heard only in the first thirteen measures of this movement prepare the listener for the overall mood of the piece.
Once the listener arrives to measure 156, the first 13 measures are repeated. However, the recurring theme is in a new key. The mixture chords used at the beginning of the piece prepare for another set of mixture chords. The listener is familiar with the theme, but surprised to hear the new key. Beethoven uses the mixture chords to his advantage by leading into a new key.
The conclusion of the piece once again returns to the introductory theme. However, this theme is shortened and has a sense of being slightly quicker than the other two. The end has the same lead in of I V7/V, but uses a short lead in to the mixture chord. In addition, Beethoven reduces the amount of accidentals at the end. This tactic allows the listener to get a true sense of the overall key of the piece. Thus, despite the confusion in between, Beethoven ends and begins with the very well know Major I chord.