Opera after 1945 largely retreated from the challenge of modernism. A survey of notable post-war music theatre locates language and its vexed relation to music as the central concern of a true modernist operatic aesthetic. I discuss the relations that bind music, philosophy and language before analysing five contemporary operas: György Ligeti’s Le Grand Macabre, Claude Vivier’s Prologue pour un Marco Polo, Helmut Lachenmann’s Das Mädchen mit den Schwefelhölzern, Salvatore Sciarrino’s Luci mie traditrici and David Lang’s The Difficulty of Crossing a Field. Each opera poses a unique challenge to the crisis of representational language, and its relation to truth, the law, and the ethics of the sensual.