May 29: Iannis is born in Braïla, Rumania to Clearchos Xenakis and Photini Pavlou, members of the Greek Diaspora (his actual birthday is uncertain: it may have been June1st, and the year may have been 1921). He is the eldest of three boys: his brother Cosmas became a painter and Jason became a professor of philosophy in the United States. Their father, a son of a farmer from Evvoia, was the director of an English import-export firm. Their mother, who spoke fluent French and German, was a good pianist. She gave Iannis a flute as a present when he was just a little boy and encouraged him to study music. The Xenakis couple attended the Bayreuth Festival several times during the 1920s.
While pregnant, his mother contacted the measles and died after giving birth to a baby girl who also did not survive. Henceforth, the children were raised by French, German and English nannies.
Iannis leaves Rumania for Greece: his father enrolled him in an English-Greek academy on the island of Spetsai. In addition to learning to love mathematics and Greek and foreign literature, Xenakis also began to discover music there.
Fall: Xenakis leaves for Athens where he enrolled in a prep school in order to prepare the competition for entering the Athens Polytechnic Institute.
He begins composing and taking private lessons with Aristote Koundourov in analysis, harmony and counterpoint. He also realized a geometric transcription of some of Bach’s works.
He succeeds in entering the Athens Polytechnic Institute, but the school is closed the first day of classes, October 28, since Mussolini’s troupes had just invaded Greece. The Institute is intermittently reopened and closed.
Xenakis joins the Greek Resistance, first in a right-wing party, then later in the EAM (communist party): he is in the front line of street demonstrations against the occupants, is imprisoned several times, first by the Italians and later by the Germans. His favorite readings include Plato, Marx and Lenin.
October 12: the Germans evacuate Greece.
December 5: the British army establishes martial law.
Xenakis joins the student battalion of the ELAS (National Popular Army) and becomes commander of the "Lord Byron" unit.
January 1: A live English shell hits the building Xenakis was defending with two of his comrades: shrapnel hit his face, smashing his jaw and poking out his left eye. Considered dead and abandoned there, his father found Iannis and took him to a hospital where he underwent several operations.
March: Xenakis is released from the hospital and goes back to the Polytechnic Institute all while continuing his political activities clandestinely; he is incarcerated several times.
February: Iannis passes his final exams successfully at the Polytechnic Institute despite his semi-clandestine existence.
January 16: defends his final thesis on "Reinforced concrete".
He escapes from a prisoner’s camp and stays in hiding for six months in an apartment in Athens.
September: his father manages to get him a falsified passport, and Iannis boards, under the name of Konstantin Kastrounis, a cargo en route for Italy. Intending to end up in the United States, Xenakis decides to visit Paris.
November 11: thanks to the help of Italian communists, he illegally crosses the border at Vintimille.
In Greece, he is given the death sentence in absentia for political terrorism. His father and brother are put into prison.
December: Xenakis is hired by Le Corbusier’s as an engineer, having been recommended by a friend of the architect Georges Candilis.
Xenakis participates in several projects and realizations.
Xenakis attempts studying composition with various professors, none of which however, correspond to his personality: Honegger at the Ecole normale de musique, and later Milhaud, who replaced the former.
He also approached Nadia Boulanger who declared she was too old to start reviewing the fundamentals of harmony and counterpoint with him. She suggested he contact Annette Dieudonné who, in turn, recommended he seek out Messiaen.
Xenakis writes twenty-four works (catalogued later by François-Bernard Mâche), mainly for piano solo ou voice and piano.
Xenakis meets Françoise.
He attends the first concerts given by the GRMC (Groupe de recherche de musique concrète), the electroacoustic ("musique concrète") studio founded by Pierre Schaeffer and attempts to joins the group, in vain.
Xenakis meets Messiaen and asks for advice. The latter invites him to audit his classes, which Xenakis does faithfully in 1952 and less regularly in 1953. There he met, among others, Karlheinz Stockhausen.
At Le Corbusier’s request, Xenakis organizes a "spatialized concert" on the roof of the housing unit in Marseille for the CIAM (Congrès international d’architecture moderne). Three different types of music are played from three different points on the terrace (musique concrète, traditional music from India and Japan, and jazz).
August: La Colombe de la paix is played at the Fourth World Youth Festival for Peace and Fellowship in Bucharest.
Xenakis begins the composition of his "Anastenaria" triptych: Procession vers les eaux claires (completed early 1953), Le Sacrifice (summer 1953), and finally, Metastasis (end of 1954).
December 3: marries Françoise.
Le Corbusier asks Xenakis to be project manager for the commission the former received two years earlier to build a monastery at La Tourette near Eveux-sur-l’Arbresle. Xenakis worked on this project until 1957:
"The general shape is Le Corbusier’s, while the internal structure was developed by me, based on discussions with the monks. […] the glass panes under the rows of cells and the church are almost exclusively my work. The same applies to the round chapels with the ‘guns of light’ and ‘machine-guns of light’ that stick out of them. I positioned them so as to catch the light of the sun during equinox." (Balint Andras Varga, Conversations with Xenakis, Faber & Faber, London, 1996, p.23)
Xenakis unveils the triple rows of his famous "undulating glass panes" on the west facade. At the same time, he is working on the composition of Metastasis, whose textures of glissandi are based on ruled parabola and graphically conceived. Two years later, he will apply the same principle in architecture, in the construction of the Philips Pavilion.
September 23: after having his score Procession vers les eaux claires returned back to him by Schaeffer, Xenakis finally manages to meet with the former, thanks to a recommendation by Messiaen. Schaeffer asks Pierre Henry to review Xenakis’s score Le Sacrifice, and Henry shows it to Scherchen during his rehersals of Varèse’s Déserts, which Xenakis attended. After stating that he wouldn’t conduct Le Sacrifice, Scherchen asks Xenakis to show him Metastasis, which he immediately offers to conduct.
Following Dimitri Mitropoulos’s advise, Xenakis also sends this score to Heinrich Strobel, the director of the Donaueschingen Festival, who programs it for the following fall, conducted by Hans Rosbaud.