In the stepwise descent Bach uses the complementary interval of a seventh to leap up before he runs out of pedal notes (i.e., a seventh is just a step with the lower note moved up an octave). But organ pedals typically have some turbocharged partials grooving along, so the leap up a seventh can easily be confused with change of tone color or even volume change on a descending step. Paired with the sustained chromatic harmony changes in the right hand, the pedal's bassline seems to be eternally descending. (Plus Bach extends this unadorned circle of fifths passage much longer than he normally would in any other piece-- if the purpose isn't to imply a potentially eternal descent I don't know what he's doing here...)
Try listening without watching the scrolling score and see if you can pick out where those pedal leaps are.
Also-- ascending new school version, now with "carriage returns":
https://youtu.be/tg50ozbZcqM?t=216
In the stepwise descent Bach uses the complementary interval of a seventh to leap up before he runs out of pedal notes (i.e., a seventh is just a step with the lower note moved up an octave). But organ pedals typically have some turbocharged partials grooving along, so the leap up a seventh can easily be confused with change of tone color or even volume change on a descending step. Paired with the sustained chromatic harmony changes in the right hand, the pedal's bassline seems to be eternally descending. (Plus Bach extends this unadorned circle of fifths passage much longer than he normally would in any other piece-- if the purpose isn't to imply a potentially eternal descent I don't know what he's doing here...)
Try listening without watching the scrolling score and see if you can pick out where those pedal leaps are.
Also-- ascending new school version, now with "carriage returns":
https://www.youtube.com/watch?v=Q6LmG9myHxA
You also get a nice simulated "Nyquist frequency" when the piano runs out of keys. :)
Edit: clarification