These two trios for the (slightly) unusual combination of soprano, alto, and bass recorders are taken from keyboard pieces by J.S. Bach. The fughetta "Nun komm, der Heiden Heiland," BWV 699, is one of several organ settings Bach made of this chorale. "Sinfonia #1," BWV 787, is the first of the so-called Three-Part Inventions of Bach, short pieces meant to teach the art of playing independent contrapuntal parts at the keyboard.