The entire musical material of the sonata comes from the chorale 'Nun danket alle Gott' as well as the notes B-A-C-H. As to its form, the sonata principally is a four-movement work the parts of which, however, immediately blend into each other, thus giving the impression of a one-movement composition. At the heart of the work are four variations in which the chorale (in the setting of J. S. Bach) is modified. Stefan Heucke