For those not familiar with Bach's Trio Sonatas for organ, they represent yet another milestone of organ composition from the German master. There are six Sonatas in all, each in three movements, and they involve (as the name implies) three musical lines in each movement: one for each of the hands and one for the feet. Registration is generally static, and the whole show is in the mastery of the dense, highly imitative counterpoint.
The feet are especially tasked here. Bach placed greater demands on the organist's feet than any composer to that point, and nowhere so much as in these pieces. The coordination required to play them at all is very impressive, and to play them well is really miraculous.
The organist, Aarnoud de Groen, is someone new to me, but he plays this movement brilliantly. (One small criticism: I do wish he had chosen a more assertive registration for his left hand, as this line gets lost a bit in this recording. But that bottom manual is for the rückpositiv, the "chair organ" which is speaking out into the church from behind his back. If this recording comes from the camera, we're hearing less of this--and more of the organ's mechanical sounds--than someone out in the church proper.)