How Does Bach Do It?

Here is one of a zillion amazing pieces that Bach has written for organ, this one perfect for Christmas. It is a little arrangement of In Dulci Jubilo (Good Christian Men Rejoice).

You will notice the melody roaming around in there but the real action is the moving material, and see if you can pick up on the two-against-three rhythm in here. You can spot it with the repeated linear blue dots, 6 of them, all in a row. It happens very fast right at the start, as if to say: "if you thought that this was going to be merely a 6/8 arrangement of the hymn you know, think again."

Keep your eyes moving and watch this bell-like pattern pass quickly from blue to purple/pink and back again. It is a pattern that reemerges in the melody line later. In the organist's hands, this 2/3 trick has to be managed by a single hand in some places, which is no small feat.