Mattheson taught—
J. F. B. C. Majer, a Swabian organist about the same time, taught—
There is no advance in these fingerings on the book by Ammerbach, published in 1571.
The right thumb it will be seen was unused, and hung helpless—the fingers being stretched out flat to reach the keys.
In order to bring the thumb into use, Bach caused the fingers to be curved and to remain over their respective keys, so as to be able to strike them accurately and rapidly. The thumbs had to pass under the fingers, and to take an equal part with them in the playing.
Bach’s method of fingering