Since the death of Pierre Boulez in 2016, the historiography of contemporary music has begun to confront the completion of one of the most remarkable careers affecting the character and context of musical life since 1945. This chapter examines the changing nature of the relationship between Messiaen and his most distinguished student. It examines Boulez’s critiques of Messiaen, and it creates a dialogue between aspects of classicism and modernism in the thinking of both composers, establishing their distinctiveness and relevance to the continuing evolution of compositional practice in the present day.

The concept of serialism appears conspicuously in the academic literature on twentieth-century music in technical, theoretical, and philosophical contexts. These various contexts, expressed over the course of much of the twentieth century, expose differing connotations of the serial concept. Part I of this chapter explores the serial concept before 1945, reflecting on the multi-dimensional origins of the concept in Arnold Schoenberg’s earliest serial compositions and the significance of Olivier Messiaen’s distinctive serial conceptions prior to the Second World War. Part II explores the serial movement in Europe after 1945, the prominent roles of the journal Die Reihe and the Darmstadt New Music Courses, and the contrasting approaches and attitudes to serialism in the United States after 1945. Tensions between rupture and continuity on both sides of the Atlantic and divergent priorities in discourse about new music demonstrate that theorising serialism entails an understanding of its dynamic disposition, instability, and impermanence.

The decade of the 1950s witnessed a great transformation in the compositional practice of Pierre Boulez. The usual narratives of serialism during this decade have tended to dwell on Boulez’s experiments with multiple serialism in Structure Ia (1951), which were tremendously short lived. His desire to expand the serial principle, however, did not end with them. Ensuing works, like Le Marteau sans maître (1952–5), Pli selon pli (1957–62/89), and the Third Piano Sonata (1955–7/63), which brought Boulez to the pinnacle of his reputation within the European circle of composers, are those that truly redefined serialism. Through this redefinition, serialism remained an important element of Boulez’s compositional technique until the end of his career. This chapter shows that Boulez’s serialism was an essential forerunner of future trends, rather than a culmination of an abandoned practice, resulting in works and approaches that opened up new avenues for composition.

Mahler’s influence among composers intensified steadily over the course of the twentieth century. Within the Austro-German orbit, his impact is evident in the music of figures as varied as Kurt Weill, Hans Werner Henze, and Dieter Schnebel. Further afield, by the mid-1920s a distinguished array of composers including Aaron Copland and Dimitri Shostakovich had begun to engage seriously with Mahler’s music. This trend would continue in the second half of the twentieth century, with the renewed attention paid to Mahler outside Central Europe giving rise to an even more diverse group of followers, including those eager to find emancipation from some of the more influential strands of postwar modernism: George Crumb, George Rochberg, Luciano Berio, Luigi Nono, Pierre Boulez, Peter Maxwell Davies, Michael Finnissy, and Jonathan Harvey. These are surveyed here with particular attention to the diverse ways in which Mahler’s influence expressed itself.