This Bach Three part invention is performed by mandolin, banjo, and bass. The piece is in three-four, I think, and definitely in a major key. It starts off with two parts playing, bass and mandolin. I thought that inventions normally started one voice at a time but maybe not. For this piece the bass has the lowest voice and the mandolin plays the highest voice. In the fourth measure the banjo comes in with the middle voice. In the first four measure the bass was playing quarter notes, I-I6-I-IV-I64-V-I or do-mi-do-fa-sol-sol-do, which are heard later in the piece. The melody is performed by the mandolin in the first three or four measures, do-ti-do-re-mi-fa-sol-mi-fa-mi-re……, and then the banjo takes that same melodic line over, very invention-esque. In about the fifteenth measure or around there the transition to the minor key begins and the melody may be heard in possibly the parallel minor. The bass often plays a more accompanying and solid line but it occasionally has some moving sixteenth notes for the piece to really be the three part invention that it is. It continues in the minor for about ten to fifteen more measures and doesn’t modulate back until the very end of the piece.
This invention would be fun to play on the piano, if possible. It would also be cool to hear this piece with even different instruments as it is in this version. The voices seem to call and respond to each other and it would even be cool to hear this on three guitars. I like how naturally the transition section sounds.