Stapert points out that in the same motet, Bach breaks off the last part of Isaiah 43:1 (du bist mein -you are mine) when the verse is first introduced. He saves is “until the point where he could introduce them as part of a brief dialogue during the chorale/fugue.” “Dialogue” implies two characters; the soprano takes the chorale - with its repeated ich bin dein (I am yours), while the basses take the response, du bist mein. The soprano chorale is the voice of the bride, the basses speak the voice of the bridegroom.

In the concluding phrase, though, the voices, having danced around each other for seven minutes or so, tie together in harmony. All voices together sing the final “du bist mein.” Who’s the “you” and who’s the “me”? Take your pick: The voice of the bride and the voice of the bridegroom has become one voice.