P = primary theme, TR = transition, S = secondary theme, C = closing section
This graph reflects how the primary themes in both exposition and recapitulation are basically, if not exactly, the same. It also reflects how the secondary theme in the exposition, whose treble line is distilled to D-C-B-A-G, is transposed back into the main key, with a distilled treble line of G-F-E-D-C. Schenkerian theory encourages the analyst to connect, as if part of a smooth melody, the prominent pitch that begins the primary theme and the prominent pitch that begins the secondary theme. This works quite well in the exposition: E is just a step higher than D. However, the stitching of the corresponding design in the recapitulation is a bit loose, particularly at the moment marked with an asterisk (*). On the one hand, the prominent pitch that begins the secondary theme in the recapitulation should be the same one that begins the secondary theme in the recapitulation, but down a perfect fifth or up a perfect fourth: in this case, D becomes G. After all, the secondary themes are typically copies of one another, differing only by their transpositional level. On the other hand, the prominent pitch that begins the primary theme in the recapitulation (E) and the prominent pitch that begins the secondary theme in the recapitulation (G) are not smoothly connected as they were in the exposition. Rather, if the prominent pitches of the recapitulation’s primary and secondary themes were to be closer together, the graph might look something like this:
But such a graph would signify a considerable change for the beginning of the secondary theme in the recapitulation from how it sounded in the exposition.
In the first movement of Mozart’s Piano Sonata in C Major, K. 279, there is such a change, although I will let the reader decide how considerable it is. This common-time movement is remarkable in how often it shifts the perceived downbeat from the notated downbeat to the spot halfway between notated downbeats. By my count, this shift happens 12 times: 6 times away from the notated downbeat, and 6 times back to the notated downbeat. Mozart does not notate these shifts, but they can be readily heard. I have notated them below for the entire movement.
I: = main key, V: dominant key, PAC = perfect authentic cadence, HC = cadence, --> = "becomes"
These shifts also affect how the beginning of the secondary theme is heard in both exposition and recapitulation. As shown below, in both exposition and recapitulation, the entrance of the secondary theme is preceded by a perception of downbeats halfway between notated downbeats. However, Mozart starts the secondary theme halfway through the measure in the exposition, while he starts it on the downbeat in the recapitulation. This changes which note in the secondary theme first receives metrical emphasis. In the exposition, that note is D. In the recapitulation, that note is not G, but E, as shown below.