As comments, Bach's son Carl Philipp Emanuel related to his biographer Johann Nikolaus Forkel how his father took pleasure in converting trios into quartets ex tempore ("aus dem Stegereif"): BWV 1044/2 is a prime example. Bach created a complex texture in this movement by juxtaposing the detached melody in the harpsichord with a parallel sustained melody in thirds or sixths in the violin or flute; and in contrast a further layer is added by the delicate pizzicato accompaniment in the fourth voice, —first in the violin and then echoed by the flute—which comes close to imitating the timbre of the harpsichord.