In August 1741, Bach - then 56 years old - made the 75-mile trip from Leipzig to Potsdam to visit his son Carl Philipp Emanuel, who for the last three years had been harpsichord player to Crown Prince Frederick of Prussia, later Frederick the Great. The elder Bach was now at a pivotal moment in his career. Earlier that same year he had given up the directorship of the Collegium Musicum, a small semi-professional orchestra in Leipzig, and he was now devoting himself increasingly to keyboard music: in the following year he would complete two of his greatest works, the Goldberg Variations and Book II of the Well-Tempered Clavier. The Sonata in E Major, completed just before this trip, was almost certainly written for the flute-playing Frederick: this music has survived only because the manuscript was later found in Frederick the Great's library.

This Sonata is the last of the three Bach wrote for flute and basso continuo: the flute line is fully written out, but there is only a single bass line for the keyboard player, whose responsibility it becomes to flesh out the harmony of the accompaniment, usually with the support of a sustaining instrument on the bass line. The brief Sonata is in four movements, all but the first of which are in binary form. The opening Allegro ma non tanto is the shortest movement in the Sonata (only 20 measures long), and its ornate melodic lines function as a sort of prelude to the three movements that follow. The second movement skips easily along its 2/4 meter, while the third moves into the relative minor, C-sharp minor. This movement is a Siciliano, an old dance form in rocking rhythms that originally came - as its name suggests - from Sicily. Bach specifies that the finale should be Allegro assai ("Very fast"), and this sparkling music is full of trills and rapid passagework.

Very probably Carl Philipp Emanuel and the future Frederick the Great gave the first performance of this Sonata in Potsdam in the presence of the composer. That would have been an evening to sit in on.

- Eric Bromberger contributes frequently to the Los Angeles Philharmonic program; he is also a regular host of the Philharmonic's Upbeat Live pre-concert events.

10/07