Pierre Boulez: It came in a very simple way. Zappa asked me to meet him. I had heard of him of course, especially in '68, '70, with the scandals about the cover for his recordings and so on and so forth. And I thought, if he asked me to meet him, it could be interesting. You never know. I met him, and found the man extremely sympathetic and interesting. Zappa wanted to break out of the kind of milieu for which he was known. I didn't know it then, but [he had] very much admiration for Varèse. Varèse was the first composer Zappa discovered who struck him so much that he became Zappa's icon. Zappa told me, "I've written some scores for orchestra, and would you consider to look at them?" I was just finished with the New York Philharmonic, and beginning with IRCAM and the Ensemble InterContemporain. So I told him, "You know I don't really conduct orchestras for the time being. If you want me to conduct a work for orchestra, you have to wait for quite a long time. But if you want to write something for the Ensemble InterContemporain, then I will perform it immediately." And so he said, "Well, I will compose for the Ensemble!" About a month later he sent me scores. I then organized an American program with a work by Carter, a work by Zappa and one by Ruggles. There may have been a work by Varèse, I don't remember exactly. It was a hard program from the point of view that I wanted the audience to take Zappa seriously, and not just as a joke. The reaction was interesting, as I expected. People who came for Carter said, "Why Zappa?" and people who came for Zappa said "Why Carter?" After that we recorded Zappa's music, in his presence. He was really a very interesting character.
JD: Did his music fascinate you?
PB: Yes. It was a beginning, what he gave to us. That was the first thing he'd composed like that. Then he had a project with the Ensemble Modern, and everybody was surprised, and they tried to catch up with him. Unfortunately he died very soon afterwards.
Jed Distler, Pierre Boulez on Composers Past and Present, 2000