The composer-performer collective l’Itinéraire, founded in 1973 by Murail and Tessier, was the de facto platform for spectral music in France. This chapter shows how l’Itinéraire formed with the aim of establishing an organ for the music of the youngest generation of French composers, and how, with the demise of Boulez’s Domaine Musical ahead of the opening of IRCAM, l’Itinéraire fortuitously found itself positioned as the successor to that Parisian new music series, endorsed by Messiaen and recipient of a state subsidy. The chapter details how Grisey composed Périodes, a l’Itinéraire commission and the first work composed from his Les Espaces acoustiques cycle, and how Grisey attended the acoustics laboratory at the Université Paris VI Jussieu, where, alongside lessons in musical acoustics, he absorbed the work of Abraham Moles on the application of information theory to art. The chapter also shows how Murail began to incorporate the models of spectral harmonicity and periodicity into his music from Tigres de verre onwards, and it explores the relationship of these instrumental compositional techniques to the computer sound synthesis work of Risset and Chowning.

D’eau et de pierre is the threshold work into Grisey’s mature music, the first work idiomatically recognisable as being in Grisey’s mature style featuring a gradually changing static ensemble texture. This chapter explores the influences on the work, showing how it tied in with the so-called meditative music of the era, in particular that of Jean-Claude Éloy and La Monte Young, each of whom was exploring long durations and static harmonic surfaces. It details Grisey’s attendance at the 1972 Darmstadt Summer Courses, where, alongside lectures and seminars by Chowning, Rădulescu, Xenakis, and Ligeti, he took part in Stockhausen’s seminars on Mantra and Stimmung. A performance of the latter by the Collegium Vocale Köln made a strong impression on him, performed by the Collegium Vocale Köln, made a strong impression on him. D’eau et de pierre was completed after this, and its form drew on Stockhausen’s concept of the degree of change of a given statistical sound.