In a nutshell, Beethoven slows down the harmonic rhythm—the rate of chord changes—toa near standstill. Early in the Development, he lingers on the B-flat major triad (B-flat, D, F), using the “motto” rhythmic motive to animate the music over an otherwise static harmony.Then the real magic comes when he “modulates” up a third to the D major triad (D, F-sharp, A), using the third of the B-flat major triad, the pitch D, as a common tone between the two chords. (You can track this change by following the double bass part in the score.) The effect is glorious! Let’s listen.Shortly thereafter, Beethoven conjures a similar magic, using the pitch B as a common tone, this time to move down a third, from the G major triad (G, B, D) to the E major triad (E, G-sharp, B). Once again, the effect is stunning!Following the E major passage, the “motto” theme appears in A major, and then a four-bar themeemerges—it’s the counter-motive we heard initially in mm. 9-16. Using this “counter-motive” as a theme, Beethoven continues a harmonic progression of falling fifths, with root motion descending from A to D to G to C, and finally back to the home key of F major.