This sonata, written in 1734, has two different catalogue numbers as it has been attributed to both Johann Sebastian Bach and Carl Philipp Emanuel Bach, his son. Some elements of the music seem to lean towards the later galant style that C.P.E. Bach wrote in, but it is officially attributed to J.S. Bach by scholars.

J.S. Bach was a German composer from the late Baroque period, born in 1685 to an already multi-generational musical family. We now attribute the Baroque period so much to his writing that we consider it to have ended at this death in 1750. He is most known for his use of counterpoint. Counterpoint is a term in music theory which refers to multiple musical lines being harmonically dependent on one another, but independent in rhythm and melody.

This piece is written for flute or violin and harpsichord, which is an instrument that would have been more commonly heard in the Baroque era. Two major differences in the harpsichord as compared to the piano are that a harpsichord plucks the strings, whereas a piano has mallets that hit the strings, and that a piano has the ability to change dynamics (hence the full name pianoforte). The first movement is in g minor, with a developmental section that explores keys such a B-flat major, E-flat Major, c minor, and f minor before returning to g minor. The second movement is a light and airy E-flat Major which touches on c minor and returns back to E-flat. The last movement is again in g minor, though it touches on d minor and B-flat Major, among other keys. This rapid changing in key is common in Bach’s music.