Karlheinz Stockhausen is one of modern music’s most controversial figures. He was at the centre of the post-war generation’s reinvention of art music in the 1950s and 1960s. By the 1970s he had become a cult figure, attracting mass audiences. His commitment to avant-garde aesthetics and religious mysticism continues to elicit extreme responses. To some, he was a fantasist whose musical gifts were less substantial than his charisma. To others, his commitment to technological innovation, particularly in electro-acoustic musical techniques, has ensured a legacy of lasting influence. Stockhausen understood his musical ambitions as an attempt to restore music to the position of philosophical and ethical significance it held in the ancient world. Recalling the ancient Greek conception of music, he remarked that ‘the highest calling of mankind can only be to become a musician in the profoundest sense; to conceive and shape the world musically.’ He argued that human imagination and sensibility was increasingly dominated by the visual field, and that we were in danger of forgetting how to use our ears to ground and orientate our awareness of the world. He considered his work as a composer in terms of an attempt to ‘re-attune’ mankind to its environment. Two aspects of Stockhausen’s childhood were crucial to his development as a composer: his attraction to the rituals and music of the Catholic Church, and his aversion to war and to Nazism in particular. In 1933, when Stockhausen was five years old, his mother entered an asylum for the insane, where she remained until her death in 1942, probably as a victim of the Nazis' euthanasia policy. His father, a village schoolteacher with a penchant for amateur theatre, wholeheartedly embraced the ideology of the regime. The continual airing of military marches on the radio left Stockhausen with a profound aversion to forced, regular rhythms and an association of music with coercion. His father’s death on the Eastern Front in 1945 left Stockhausen orphaned. He enrolled in the Cologne Musikhochschule in 1947, graduating in 1951. He took composition lessons with the Swiss composer Frank Martin, and considered a career as a writer, encouraged to do so by his early hero, the novelist Hermann Hesse. But it was Hesse’s espousal of a holistic philosophy of music in his novel The Glass Bead Game that proved most influential. In 1951 Stockhausen attended the avant-garde music summer school at Darmstadt, where he discovered the music of Messiaen. Attracted by the Frenchman’s experiments in timbre and rhythm, he travelled to Paris, studying in Messiaen’s composition classes. In Paris he met the composers Pierre Boulez and Pierre Schaeffer, whose experiments with musique concrète (electronically produced and manipulated sound) proved formative. Stockhausen’s first composition for tape, Konkrete Etüde, dates from this time. Even at this stage, however, he cut a fiercely independent figure. Schaeffer later remembered him as ‘absolutely unwilling to follow my advice’. Stockhausen returned to Cologne after a year in Paris, and many of his most seminal works date from this period. Together with his teaching in Cologne and Darmstadt, works such as the set of piano pieces, Klavierstücke (1954–5), and Gruppen (1955–57) cemented his reputation as one of the central figures in the European musical avant-garde. A successful extended lecture tour in the United States in 1958 widened his influence further still. By the end of the 1960s he had become one of the world’s most widely recognised and best-selling composers. He travelled widely, invited to perform his music all over the world, often in unorthodox or outdoor venues. In the spherical German pavilion of the 1970 World Expo in Osaka, Stockhausen and a team of musicians performed his music daily for six months. From 1977 onwards, Stockhausen concentrated his efforts principally on the composition of his grand cycle of seven operas. Entitled Licht (Light), the individual operas were to be named after the days of the week and would present a version of the creation myth. In this cycle, the struggle between Lucifer and the archangel Michael would lead to the ‘rebirth, in music, of mankind’ through the third character of Eve. The scale of the project led Stockhausen to entrust some of the composition to three of his children (Markus, Majella and Simon), and two of the women who lived with him in the house he designed and built in Kürten, outside Cologne. Composed over 26 years and completed in 2003, Licht provides a good key to Stockhausen’s changing attitude to style and the renewed growth of his interest in electro-acoustic and other unorthodox sources of musical sound. In their use of ritual and the use of several singers and instrumental combinations to present each character, the cycle departs significantly from the orthodoxies of music drama. Long sections proceed without voices. Another infamously requires each member of a string quartet to perform their part in a different airborne helicopter. Stockhausen’s last major composition, Klang (‘Sound’) was intended as a cycle of 24 chamber works, each devoted to an hour of the day and intended to reconcile our awareness of time with the activity of listening. Filled with long silences and patient explorations of particular pitch-combinations and timbres, the pieces are of a vastly different style from the angular and busy worlds of Gruppen and Klavierstücke. Although he composed the pieces at unusual speed, Stockhausen did not live to complete Klang. He composed 18 works in the cycle before he died suddenly of heart failure.