Passed down to us through almost two millennia, the poem that would later become "Savior of the Nations, Come" was set to a plainchant melody in the Middle Ages, and that melody was given a strong, angular treatment by Martin Luther, who also adapted and translated the text.  A couple centuries later, it was Bach's turn to create something new from this storied hymn -- and he did, multiple times.  This organ prelude may be one of Bach's more austere arrangements of this hymn, but he couldn't help adding some clever complexity to it.

We talk about how an extended ending can add much-needed closure to a piece.  We also talk about how Bach is like a stained glass window -- colorful, complex, subtle, beautiful, illuminating core religious truths.

BWV 659 played by Leo van Doeselaar for the Netherlands Bach Society:

https://www.youtube.com/watch?v=K2ANMpDoRow