If Gregorian chant is the Catholic Church's very own music after the Council, then Hummel's organ music is particularly characterised by this idea - here again one of his answers quoted above applies: Gregorian chant is indispensable as a source of inspiration for all genuine church music. After Gregorian chant, hymnody is the next source of inspiration. If it is not direct passages or particles from Gregorian chant or hymns, then Hurnmel invents modes as building blocks, which are modified as tone sequences from memory or from models and with which it is possible to work contrapuntally and harmonically.
This way of working can be seen and heard particularly clearly in the short pieces he wrote for the "Augsburger Orgelbuch für den gottesdienstlichen Gebrauch". (Four volumes published by Böhm & Sohn, Augsburg). These are: a prelude in d (booklet 2), an improvisation: "Komm, Schöpfer Geist" (GL no. 245) (booklet 3) and a postlude: "Laßt uns erfreuen herzlich sehr" (GL no. 585) (booklet 4).

In the prelude, a six-note sequence runs through the whole piece in all possible variations. Even if one cannot speak of a half twelve-tone row, it is interesting in this context that Hummel rarely uses the strict twelve-tone compositional technique because he wants to determine his own parameters for the composition.

(from Franz A. Stein, "Die Kirchenmusik Bertold Hummels", Tutzing, 1998)