Greens Farms Academy is a PreK-12, coed school in Westport, CT

"Two-Part Piano Invention"

By McKenna Mercurio Morse '24

Throughout the duration of our Music Theory class this spring semester, I have learned all about the ways different musical compositions are constructed and how to apply these concepts to my very own piece writing. We have studied things such as cadences, the makings of a 12-bar blues, inversions, and figured bass, all of which are necessary in composing a piece.  

The idea of a two-part invention originally came from J.S. Bach, who composed “teaching pieces that appear in ascending order by pitch, starting with C and using only those Major and minor keys with no more than four sharps or flats.” Throughout his life Bach created 15 of these "inventions," mainly for his then-12-year-old son, Wilhelm Friedemann Bach.

In a two-part invention, the first voice or part plays the main theme while the other accompanies in free counterpoint. The voices then switch, with the second voice playing the main theme and the first providing counterpoint. Inventions can also have counter subjects that accompany the main subject of the piece.

In class we started by taking a look at Bach’s inventions and seeing how we could model ours in a similar way. We then discussed all the things necessary for a two-part invention and worked those into our pieces. My piece titled, "Two Part Piano Invention" consists of a right-hand piano beginning playing the main theme and a left-hand accompanying free counterpoint. The entire piece is written in the key of C major. I really enjoyed composing this piece!