Hermann Schroeder (1904–1984) ranks among the major German organ composers of the 20th century, being an excellent organist himself. Many of his more than 100 organ works deal with themes of the Gregorian chorale. The chorale's modal diatonicism which is freer and different than the later major-minor tonality establishes a perfect symbiosis with the free tonality of the contemporary composer. In the five-movement chorale partita, the more than 1,000 years old Mixolydian Whitsun Sequence of Hraba...