In the post-war period Poulenc crossed swords with composers of the younger generation who rejected Stravinsky's recent work and insisted that only the precepts of the Second Viennese School were valid. Poulenc defended Stravinsky and expressed incredulity that "in 1945 we are speaking as if the aesthetic of twelve tones is the only possible salvation for contemporary music". His view that Berg had taken serialism as far as it could go and that Schoenberg's music was now "desert, stone soup, ersatz music, or poetic vitamins" earned him the enmity of composers such as Pierre Boulez. Those disagreeing with Poulenc attempted to paint him as a relic of the pre-war era, frivolous and unprogressive. This led him to focus on his more serious works, and to try to persuade the French public to listen to them. In the US and Britain, with their strong choral traditions, his religious music was frequently performed, but performances in France were much rarer, so that the public and the critics were often unaware of his serious compositions.