On February 4, the world lost one of the greatest composers and musical thinkers of our time, Iannis Xenakis. Born in 1922, his education led him to the Polytechnic School in Athens, where he graduated as a civil engineer in 1947. During World War II he was a member of the Communist resistance in Athens and was injured by a shell fragment from a British tank, losing his left eye and severely scarring that side of his face. He was condemned to death because of his activities during the war, and fled to France in 1947. Though he originally planned to go to the United States, he remained in Paris, where he joined Le Corbusier’s architectural firm. While working with Le Corbusier, he contributed to some of the twentieth century’s most innovative designs: the Philips Pavilion for the Brussels World’s Fair of 1958 replaced ordinary planar construction with flowing surfaces based on the continuous displacement of the straight line. Having had some musical training in his youth, Xenakis resumed his studies in Paris, attending classes taught by Olivier Messiaen at the Conservatoire. He would eventually concentrate exclusively on composition, but his musical works always bore a strong relationship to the mathematical thinking he also incorporated into his architecture.

Although Xenakis was certainly multi-talented, there were more important reasons for him to make links between different disciplines. His music embodies an ideal akin to that of the ancient Greeks, in which the arts, particularly music, are branches of human intelligence. He felt that these different branches of intelligence should inform one another, using mathematics as the common ground through which universal ideas may be shared. This notion is reflected in the diversity of his own artistic output, which includes chamber music, orchestral music, electronic music, and combinations of music and laser light projections such as Polytope de Montréal, presented during Expo 67.

Xenakis employed many different mathematical models in his music. His first major composition, Metastasis (1954), for orchestra, translates lines like those of the Philips Pavilion into huge networks of glissandi. The systems he began to devise in the early fifties were partly a reaction against serial technique, which was widely used by other composers at that time. He argued that while serial procedures were basically polyphonic in conception, the complex textures which resulted were heard as "a mass of notes in various registers," not as polyphony. Xenakis turned to a mathematical model which was designed to deal more adequately with complex textures. He coined the term stochastic music. As in probability theory, in stochastic music dense textures which he called "clouds" or "galaxies" had so many components that the behaviour of each individual component could not be determined, although the composite musical effect could be. This conception can be heard clearly in his second orchestral piece Pithoprakhta (1956). The composer likened the principles of stochastic textures to those involved in natural sound phenomena such as "a collision of hail or rain with hard surfaces, or the song of cicadas in a summer field."

In the two decades which followed the composition of Pithoprakhta, Xenakis continued to use stochastic principles, and also incorporated ideas from set theory and symbolic logic into his music. Meanwhile, he increasingly used computers for the complex and numerous calculations involved in the composition process. As machines became more powerful and the programs designed by the composer became more sophisticated, computers actually injected more freedom into Xenakis’ creative process. By 1979, his UPIC system was able to translate graphic ideas into musical results. Drawing always played a major part in the former architect’s thought process, and in the seventies, his sketches frequently took the shape of what he called arborescences, sets of organic curves branching out into tree-like formations. Points on these curves would be interpolated to dictate musical elements, especially pitches within melodic lines. This method of working, like that of the first stochastic pieces, placed the conceptual emphasis on texture, and the result was bold gestures which make Xenakis’ work of the seventies some of his strongest. Phlegra (1975), for eleven instruments, is a good example of this type of clarity. The eerie sound world of N’Shima (1975) created by quarter tones and the unusual scoring for two amplified peasant voices, two horns, two trombones and amplified cello proves beyond a doubt that computers and mathematical models were anything but a limitation on the composer’s imagination.

Xenakis’ personal voice speaks through much of his music in a way that demonstrates both his musicality and his ability to create systems which promoted this musicality. Several books that he wrote, particularly Formalized Music (1963), go into great detail concerning the mathematical models and computer algorithms he used. Little is written, however, on the role intuition played in his compositions, although he maintained that it is present, and the personal character of the music supports this fact. Indeed, while it is not difficult to appreciate the clear powerful forms in Xenakis’ music, it is very difficult to know which elements of the music are the results of systems and which are the products of his intuition. In general he avoided speaking about the personal significance of his music, and this may well be because the significance was often painful to him. Occasionally he would reveal that the sentiment of his music was derived from his experiences during the war, or that stochastic principles not only mimic the structure of sounds in nature but also the sound of a crowd of demonstrators chanting and then being dispersed by machine-gun fire. Judging from a later work, Dämmerschein (1994), for large orchestra, the violence he experienced in the forties continued to affect his music throughout his life.