The second theme in the exposition is supposed to be in dominant in classical sonata style. In this piece, nevertheless, the composer placed the second theme in a more remote key area- the mediant (B-flat major). As shown in Fig. B, the arpeggiando passage in the transition (mm.38-45) seems to establish the dominant- D major, preparing the use of the dominant in the second theme. However, the listeners are once again tricked as the restatement of the first theme in G major quickly leads to a modulating passage, reinforcing the dominant of the mediant (B) The sudden shift to B major(m.65) and the light character of the second theme (Fig .C) contrasts sharply with the weighty first theme in the home key. This arrangement is wakening as Beethoven tried to make his listeners believe he was using traditional harmony for the second theme by introducing the D major passage but dawn them with realization when he abruptly stated the theme in the mediant. Fig. B
Recapitulation in the classical sonata convention usually indicates double return i.e. the return of home key and the return of themes. The second theme is supposed to be set in the home key, in this case, G major. However, the composer once again showed his determination in experiencing innovative harmonic writing in this movement. The second theme (Fig. D) in the recapitulation does not simply return to G major. Instead, it is set in E major (mm.217-224), the submediant of the home key in the beginning, building a surprising elevation of both the key area and the lightness of the music. When the second theme returns to G major (m.233), the listeners may as well consider it as the resolution of the tension created by the E major. Yet, the composer did not think along the same line. The tonicisation in b minor (Fig. E) (mm.248-252) poses a question : Did the composer want a double return in the recapitulation or not? At the times of the composer, it is a norm to set the second theme in the recapitulation in the home key with clarity. His innovative idea of suggesting harmonic ambiguity here most likely makes the listeners taken aback and excited. The listeners may be lured to find the exit of the maze created by the harmonic ambiguity.
The perfect cadence of G major (Fig. F ) in mm. 254-255 suggests final return to G major after wandering in E major and b minor. Nonetheless, the cadence is...