[6] Among the numerous theoretical writings he authored, the book Formalized Music: Thought and Mathematics in Composition (French edition 1963, English translation 1971) is regarded as one of his most important publications.

[citation needed] Giannis Klearchou Xenakis was born in Brăila, Romania—which at the time had a large Greek community, as the eldest son of Greek parents; Klearchos Xenakis, a businessman from Euboea who was managing director of an English export-import agency and one of the richest men in the city, and Fotini Pavlou from Lemnos, a pianist who also spoke German and French.

[3] His two younger brothers were Jason, who became a philosophy professor in the United States and Greece, and Kosmas [el], an architect, urban planner and artist.

[7] He was subsequently educated by a series of English, French, and German governesses, and then, in 1932, sent to Greece to study at the Anargyrio-Korgialenio boarding school on the Aegean island of Spetses.

[3] He excelled in both academics and athletics and sang in the school's boys' choir, where the repertoire included works by Palestrina, and Mozart's Requiem, which Xenakis memorized in its entirety.

In 1938, after graduating from the school, Xenakis moved to Athens to prepare for entrance exams at its National Technical University, also studying Ancient Greek.

In December 1944, during the period of Churchill's martial law,[12] Xenakis (who was by then a member of the communist students' company of the left-wing Lord Byron faction of ELAS) became involved in street fighting against British tanks.

He was wounded and facially disfigured when shrapnel from a tank blast hit his cheek and left eye, which was blinded;[13] the fact that Xenakis survived the injury has been described as a miracle.

He worked as an engineering assistant at first, but quickly rose to performing more important tasks, and eventually to collaborating with Le Corbusier on major projects.

These included a kindergarten on the roof of an apartment block in Nantes (Rezé), the Unité d'Habitation of Nantes-Rezé, parts of government buildings in Chandigarh, India, the "undulatory glass surfaces" of Sainte Marie de La Tourette, a Dominican priory in a valley near Lyon, and the Philips Pavilion at Expo 58—the latter project was completed by Xenakis alone from a basic sketch by Le Corbusier.

[19][page needed] The experience Xenakis gained played a major role in his music: important early compositions such as Metastaseis (1953–54) were based directly on architectural concepts.

Xenakis, who was by that time well acquainted with music of Debussy, Béla Bartók, and Stravinsky, all of whom used such devices and much more experimental ones, was furious and left to study with Darius Milhaud, but these lessons also proved fruitless.

Messiaen's modal serialism was an influence on Xenakis's first large-scale work, Anastenaria (1953–54): a triptych for choir and orchestra based on an ancient Dionysian ritual.

[19] He was considered to be part of the Darmstadt School, but later broke with the group of composers, who he believed focused too heavily on serialism and controlling all aspects of composition.

In 1957, he received his first composition award, from the European Cultural Foundation, and in 1958 the first official commission came through, from Service de Recherche of Radio France.

[31] After leaving Le Corbusier's studio in 1959, Xenakis supported himself by composition and teaching, and quickly became recognized as one of the most important European composers of his time.

His notable students include Pascal Dusapin, Henning Lohner, Miguel Ángel Coria, Susan Frykberg, Norma Tyer, Robert Carl, and Julio Estrada.

Polish musicologist Zbigniew Skowron, describing Aïs, wrote "In accordance with his atheist views, Xenakis emphasizes the finality of death as the ultimate event of human life, and this is probably why wild shrieks and moans punctuate his score".

Persephassa, commissioned by the Shiraz Arts Festival, was performed by Les Percussions de Strasbourg, receiving its world premiere in Persepolis in 1969.

[38] Although electroacoustic compositions represent only a small fraction of Xenakis's output, they are highly relevant to musical thinking in the late 20th century.

Important works in this medium include Concret PH (1958), Analogique B (1958–59), Bohor (1962), La légende d'Eer (1977), Mycenae-Alpha (1978), Voyage absolu des Unari vers Andromède (1989), Gendy301 (1991), and S709 (1994).

Elastic barriers or mirrors are used to keep the randomly generated values within a given finite interval, so as to not exceed limits such as the audible pitch range, avoid complete chaos (white noise), and to create a balance between stability and instability (unity and variety).

"[44] Ben Watson expressed admiration for the "terrifying emotional impact of [Xenakis'] sonic objectivity", describing his music as possessing "truly majestic otherness.

"[45] Tom Service praised Xenakis' music for its "shattering visceral power" and "sheer, scintillating physicality", noting its "deep, primal rootedness in richer and older phenomena even than musical history: the physics and patterning of the natural world, of the stars, of gas molecules, and the proliferating possibilities of mathematical principles.

"[13] Service described Xenakis as a composer "whose craggily, joyously elemental music turned collections of pitches and rhythms and instruments into a force of nature, releasing a power that previous composers had only suggested metaphorically but which he would realise with arguably greater clarity, ferocity, intensity than any musician, before or since," and suggested that his music is "expressive: not in a conventionally emotional way, perhaps, but it has an ecstatic, cathartic power.