It was long believed that most of Bach's chamber music dated from his period at the German court of Cöthen, a post he held from 1717 to 1723. But more recent research into works such as the present Sonata for Flute and Harpsichord has complicated that assumption and enriched our understanding of Bach's compositional process. It is a work whose combination of tradition and innovation side-by-side tells us something about its origins.

The Bach scholar Christoph Wolff has offered several compelling arguments in favor of dating this sonata to Bach's Leipzig period, specifically to the 1730s. Bach was director of the Collegium Musicum in Leipzig at the time, and the sonata was just the sort of music the Collegium included in its concerts. Bach's children frequently performed with the Collegium, and Bach may have intended the sonata for his son Johann Gottfried Bernhard (1715-1739), a gifted flute player. The Sonata exists in at least one earlier version, in G minor with a part for concertante harpsichord, parts of which were probably a revision of an even earlier trio sonata. (For tonight's performance, a cello joins the ensemble to reinforce the harpsichord part.)

The music of the B-minor Sonata combines elements of both of these styles. The structure of the opening movement, with its alternation between fuller-textured, ritornello-like passages and stretches dominated by the soloistic writing for the flute, reflects its debt to concerto form. In the ensuing Largo e dolce, too, Bach writes for the harpsichord as he would for the ripieno (the orchestra) in one of his concertos, and the flute spins out its melody as a soloist. The closing movement begins with a Presto fugue written in three voices - flute, keyboard right hand, and keyboard left hand - in the manner of a trio sonata. The concluding Allegro, a dance movement in 12/16, continues this kind of writing.

- John Mangum holds a Ph.D. in history from UCLA. He is the Los Angeles Philharmonic's Program Designer/ Annotator.