The piano piece *Invocation 52*, Op. 7, was my first – somewhat unconventional – compositional exploration of Arnold Schoenberg’s serial technique. Bitonal harmonies, which coalesce into a 12-tone whole, coexist with a dissolution into lines, each supported by sustained notes and varied rhythmically. The formal framework is provided by two ‘invocations’ that are identical in terms of their tonal material, each ending on the note E flat and finally fading away at ppp.

Bertold Hummel

There are hardly any fixed structures here; the entire piece of music is constantly dissolved into arabesque-like lines, thoroughly rhetorical. ‘Invocation’ means something like an invocation or incantation. This music derives its life entirely from the sonic experience and has an almost magical effect. Compared to the sound, the structure takes a back seat. And yet there is also a component in this music which – as is so often the case with Hummel – betrays the calculating mind: After 10 rhapsodic introductory bars, a four-bar section follows which, through its layering of thirds, piles up six notes into major and minor chords, thereby exemplifying Zarlino’s dual principle (bars 10–14). These four bars are followed by 24 bars of free rhapsodic music, which, despite their loosely woven texture, establish the formal framework. It is noteworthy that this fermata at the end of the four-bar section shown above is situated more or less exactly at the ‘golden ratio’!

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