Friederich Griepenkerl, in his 1844 introduction to Volume 1 of the first complete edition of J. S. Bach's organ works, wrote: "Actually the six Sonatas and the Passacaglia were written for a clavichord with two manuals and pedal, an instrument that, in those days, every beginning organist possessed, which they used beforehand, to practice playing with hands and feet in order to make effective use of them at the organ. It would be a good thing to...