Xenakis publishes "Vers une philosophy de la musique" (Towards a philosophy of music) in the Revue d’esthétique, vol. 21 n° 2-3-4 (a first version of this text was published in 1966 in the Gravesaner Blätter). In this essay, he again discusses the differentiation between outside-time and in-time and explains how he applied rotating cubes in his composition of Nomos Alpha.
April 7: Nuits is premièred at the Royan Festival (which commissioned the work) by the soloists of the ORTF (French Radio) Chorus, conducted by Marcel Couraud. It is an absolute triumph.
October 25-31: the first Contemporary Music Days in Paris, successor event to the International Music Week in Paris (SMIP), which began in 1958.
Each of the four days concentrated on one composer: Varèse, Xenakis, Berio, Henry.
October 26: "Xenakis Day":
At 2:30 pm, at the Paris Museum of Modern Art: an interview-debate around the EMAMu.
At 6:15 pm, at the Théatre de la Musique: concert given by the Ensemble instrumental de musique contemporaine de Paris, conducted by Konstantin Simonovitch, with Jacques Wiederker (French première of Les Suppliantes, then Nomos Alpha, Analogiques A&B, Eonta).
At 9:00 pm, concert given by the Orchestra national et de la Maîtrise de l’ORTF (French Radio orchestra and chorus), conducted by Lukas Foss, with soloists from the same chorus, and a sound installation by the GRM: Metastasis, Bohor,Polla ta Dhina (French première), the world première of ST-48, and finally, Nuits.
"Xenakis gets set up in the middle of the concert hall in order to control the performance of his Bohor from the electroacoustic console. In total darkness, and little by little, an extravagant uproar builds, leading to an absolutely unbearable flood of sound. […] During intermission, everyone was talking only about the "traumatism" of Bohor […] However, in just a few minutes, all of the copies of Nuits were taken from the chorus’ stands by members of the audience, undoubtedly avid to know more about the ‘man of the day’." (Michel Granlet, "Le journal des journées", La Revue Musicale. Carnet Critique, n°267, p.16.
"Xenakis is ‘catching on’. […] All these concerts were sold out and for some, people were turned away. […] Perhaps the gap between creator and public, which has grown incessantly since Beethoven, is finally being filled?" (Claude Rostand, Le Figaro Littéraire, November 11-17, 1968.
Louis Leprince-Ringuet welcomes the EMAMu in the Collège de France’s nuclear physics laboratories. The research being done among this team is beginning to attract attention.
April 2: at the Royan Festival, Paolo Bortoluzzi performs a choreography by Béjart on Nomos Alpha, that Xenakis finds pleonastic.
April 4: also at Royan, Nomos Gamma is premièred by the ORTF (French Radio) Philharmonic Orchestra, conducted by Charles Bruck.
June 2: At the inauguration of the National Arts Center in Ottawa, the première of Xenakis’s ballet Kraanerg, conducted by Lukas Foss, and choreographed by Roland Petit, with stage design by Vasarely, is given.
July 3: Anaktoria is premièred by the Paris Octet at the Avignon Festival.
Spetember 9: Persephassa is premièred by the Percussions de Strasbourg at the Shiraz Arts Festival (Iran).
October 28: French première of Persephassa at the Contemporary Music Days (Paris).
Osaka World Fair: presentation of Hibiki Hana Ma, an eight-track electroacoustic piece, within a performance including laser beams.
"There, Xenakis observed that beams of pure light, homogenous and undiffused, are somewhat like continuous sound. […] light flashes would, in a sense, correspond to string pizzicati as laser beams would to glissandi." (Jean Miller, Le Diatope, geste de lumière et de son, CNAC, Centre Georges-Pompidou, 1978).
May 21: first performances of works by Xenakis in Chili: Metatstaseis and Pithoprakta, by the Philharmonic Orchestra conducted by Juan Pablo Izquierdo at the Santiago Municipal Theatre.
April 6: Royan Festival: premières of Charisma (written in memory of Jean-Pierre Guézec), by Guy Deplus and Jacques Wiederker and of Synaphaï, by the ORTF (French Radio) Orchestra, conducted by Michel Tabachnik.
May: Monographic concert in the Composer’s Showcase at the Whitney Museum of American Art, New York.
August 24: première of Aroura at the Lucerne Festival by the Festival Strings and Rudolf Baumgartner.
August 26: première at the Shiraz Art Festival (Iran) of Persepolis in the ruins of Darius’ palace.
"[…] this work will be a landmark in the evolution of one of the most speculative and general philosophies of our time, especially by its annexation of vast acoustic and visual spaces and by placing living human presence within a mechanism that is dominated by musical logic." (Maurice Fleuret, Nouvel Observateur, September 6, 1971).
October 18: world première of Duel (written in 1959) in Hilversum by the Radio Orchestra, conducted by Diego Masson and Fernand Terby.
October 27: première of Mikka by Ivry Gitlis at the Museum of Modern Art, Paris.
November 29: at the Theatre de la Ville (Paris), concert entirely dedicated to Xenakis by the Domaine Musical: Herma, Diamorphoses, ST/10, Aroura (French première), Hibiki Hana Ma (4-track version), and Eonta.
Musique. Architecture is published by Casterman. This book comprises articles previously published in various periodicals.
April 26: English Bach Festival: première of Linaia-Agon.
Xenakis is nominated an honorary member of the British Computer Arts Society.
Michel Guy commissions Xenakis to write an opera. His response:
"No, I’m not interested, but I can create an automated, abstract spectacle with lights, lasers and electronic flashes." (Il faut être constamment un immigré, op.cit., p. 114).
This was to become the Polytope de Cluny, premièred on October 13, 1972 and presented until January 1974. In all, nearly 100,000 tickets were sold. Installed within the Roman baths of Cluny on boulevard Saint-Michel in Paris, the light show was generated by a computer that controlled the 600 some white electronic flashes and 400 mirrors that reflected green, red and blue laser beams. The sound element was an 8-track electroacoustic tape that Xenakis realized in the Studio Acousti.
The EMAMu becomes the CEMAMu (Centre de Mathématique et Automatique Musicales). It is henceforth equipped with a digital/analog converter that was built by Alain Profit at the CNET (Centre national d’études des télécommunications, National center for telecommunication studies).
"Xenakis Days" at the music department of the University of Montreal.
July: Xenakis is invited to teach at the Darmstadt summer session. He will again return there in 1974 and 1990.
Fall: Xenakis begins his career as Associate Professor at the Université de Paris I, in the visual arts and the sciences of art department. He institutes a seminar called "Formalization and programming in the visual arts and music".
December: Xenakis goes to Bali and Java on a trip organized by Maurice Fleuret (with Betsy Jolas, Toru Takemitsu and Marie-Françoise Bucquet).