Boulez, Leibowitz and aesthetic protests

The final key influence on the young Boulez was the Second Viennese School. Schoenberg, Berg and Webern were very little known in France in the mid-1940s, and René Leibowitz (1913–72) can be credited with introducing Boulez to these composers, whatever their subsequent disagreements. Most publications on Boulez highlight the importance of Webern's serial language to the young composer, but Schoenberg was arguably a stronger influence on his earliest works. Michel Leiris's article on Schoenberg, first published in a programme book for one of Leibowitz's concerts, ends with words that could equally apply to Boulez:

It was the hyper-emotional, expressionist Schoenberg that Boulez knew before February 1945, when he attended a concert at the home of Claude Halphen, a young supporter of contemporary music. Boulez told Antoine Goléa that this was

This prompted Boulez to attend Leibowitz's private classes from spring 1945 to autumn 1946, again as part of a group of fellow private students of Messiaen including Nigg, Grimaud and Loriod. Nigg told Jean Boivin that he instigated the ‘defection’ of Messiaen's students to study with Leibowitz, whom he had met through his first French pupil, André Casanova (1919–2009).

February 1945 also witnessed one of the most notorious events involving the group of students. Stravinsky's Danses concertantes (1941–2) was given a Paris premiere on 27 February 1945 by the Société Privée de Musique de Chambre, and a small group of Messiaen's students, led by Boulez, protested against what they perceived as the old-fashioned neoclassical style of this work, shouting and blowing police whistles.