The piano piece Invocation 52, op. 7 was my first compositional - somewhat unconventional - exploration of Arnold Schönberg's row technique. Bitonal harmonies, which form a 12-tone total, are juxtaposed with a resolution into lines, each of which is supported by sustained notes and varied rhythmically. The formal framework is formed by two "calls" that are identical in terms of tonal material, each ending with the note e flat' , finally fading away in ppp.

Bertold Hummel

There are hardly any fixed structures here; the entire music is permanently dissolved into arabesque-like lines, rhetorical through and through. "Invocation" means something like invocation or incantation. This music lives entirely from the sound experience, has an almost magical effect. The construction takes a back seat to the sound. And yet there is also a component in this music which - as so often with Hummel - betrays the calculator: 10 rhapsodic introductory bars are followed by a four-bar section which, in its layering of thirds, piles up six notes to form major and minor chords and thus exemplifies Zarlino's dual principle (bars 10-14). These four bars are followed by 24 bars of free rhapsody which, despite their loosely worked texture, create the formal framework. It is remarkable that this fermata at the end of the four bars shown above is more or less exactly at the place of the "golden section"!

Klaus Hinrich Stahmer (in "Die Kammermusik als persönliches Bekenntnis", Tutzing, 1998)