A transverse flute accompanies the tenor voice in the aria "Ermuntre dich: dein Heiland klopft" (Be lively now, your Savior knocks). The knocking is expressed in repeated notes.Throughout the movement, a motif identified by Albert Schweitzer as a joy motif pictures an "almost breathless expression of personal euphoria". The demanding flute part was probably composed for the excellent flute player for whom Bach first wrote a few weeks earlier in Was frag ich nach der Welt, BWV 94, and then in other cantatas during the fall of 1724.