In four notes, Bach reframes our idea about what is possible in common practice harmony.  This is one of the weirdest moments of Bach, coming from one of the weirdest openings to a hymn tune.   But as always, it makes sense in the context of the text.  It even makes sense harmonically, as we see when the hymn tune closes on four much more normal-sounding notes... and Bach repeats these, adding closure to the text "es ist genung" (it is enough).   This little repetition at the coda, even more than the wildly inventive opening, shows the genius of Bach, the subtle choices that make him enduringly great. Netherlands Bach Society performs the closing chorale of O Ewigkeit, du Donnerwort (BWV 60) under the direction of Shunske Sato