Psappha

Bálint András Varga: Rhythm in your recent music has become conspicuously simple and metrical. A particular rhythmic pattern may expand over a long stretch of the score and the effect is not unlike minimal music.
Iannis Xenakis: The reasons are threefold. First of all I come from a place where these rhythms – and I’m happy to call them Bartókian rhythms – are indigenous. They are traditional in Greece, not so much in Romania, and also in Bulgaria. I was brought up on them. I have studied and been attracted by Indian rhythms: based on very simple elements, they are highly complex: You take one pattern – say 2–3–3; then you expand it by moving the beat (the down-beat, for instance) just one unit, and then go back to the original pattern. This creates a discrepancy in your mind. We’re very sensitive to equal rhythm: it’s like the movement of a train. If you shift it by just one unit, you’re shaken out of it. This is very important from both an aesthetic and a psychological point of view. I studied Indian percussion music a long time ago – not to imitate it but to understand the underlying principle, these shifts of rhythm which produce a multi-layered system even on a single instrument. In Psappha, for instance, the accent produces several layers of rhythmic patterns, superimposed one on another, all with just one performer. Of course, it’s quite a challenge for the percussionist. Thirdly, I’ve also studied African rhythms, which also appear to be complex but in fact are based on isochronic rhythmic patterns. Again, they’re very close to my axiomatics of complex pitch or rhythm structure, based on a pattern which repeats several moduli simultaneously. It’s this structure that serves as a tool to produce polyrhythms. You mentioned minimal music. That’s simply a by-product of Indian or African music. In fact, however, it has always existed. Bach is repetitive – like a motor. In the past I experimented with music without a rhythmic pulse, that is, having no precise rhythmic sense. In my latest pieces I seem to have come back to very sharp and simple structures that are immediately perceptible.
(Bálint András Varga: Conversations with Iannis Xenakis. London: Faber and Faber 1996, p. 146 f. See also p. 179.)