While something of a scholarly consensus has been reached in regard to the sonata formerly listed as BWV 1020 (see the program notes for the C. P. E. Bach G major sonata on this program), the origins of many of the solo flute works still attributed to J. S. Bach are still unknown and their true origins have given rise to many theories, some more far-fetched than others.

Sonata in E-flat major for flute and harpsichord, BWV 1031

This work is sometimes credited to C. P. E. Bach as well, although the manuscript (in Emanuel's hand) clearly credits it to his father. Bach scholar Christoph Wolff has hypothesized that this was an exercise piece, in which the elder Bach provided the basic outline for his son to flesh out, with some final editing by Johann Sebastian; others have suggested that C. P. E. used this work as his model for the G minor flute sonata. Regardless of who actually composed it, the finale of the E-flat major sonata — unusual in that it is nearly as long as the first two movements combined — features one of the most recognizable melodies among all of the works on this program. Like BWVs 1030 and 1032, BWV 1031 is an example of an obligato sonata, one in which the right-hand notes of the accompaniment are fully written out; in contrast, BWVs 1033-1035 are continuo sonatas, in which only the bass line of the accompaniment is provided.

Sonata in E major for flute and continuo, BWV 1035

In the summer of 1741 Bach journeyed to Berlin. While he did not meet his son's employer, Frederick the Great (who had succeeded to the throne the previous year), on this journey — that famous meeting would not happen until 1747 — Bach did encounter the king's chamberlain, Michael Gabriel Fredersdorf. Like the king, Fredersdorf was an accomplished flutist, and an early manuscript copy of the E major sonata seems to indicate that Bach wrote the work for the chamberlain during the course of this visit.

Sonata in E minor for flute and continuo, BWV 1034

Surviving performance materials indicate that this work was composed no later than about 1724.

Partita in A minor for solo flute, BWV 1013

Bach conceived of his music through polyphony — the use of two or more voices simultaneously — so it is all the more remarkable that he wrote so much great music for single melody instruments, such as the six cello suites, the solo sonatas and partitas for violin, and this work for solo flute.

Sonata in A major for flute and harpsichord, BWV 1032

Like BWV 1030, this work was composed no later than 1737.

Sonata in C major for flute and continuo, BWV 1033

The earliest surviving materials for this work date from 1731.

Sonata in B minor for flute and harpsichord, BWV 1030

Bach's B minor sonata is generally considered his greatest. Its expansive opening movement is the longest first movement of any of his sonatas.