Possibly the most important musical revolution of the 20th and 21st centuries has been the emergence of sound, and the ever-greater importance accorded to it (cf. Solomos 2019). Xenakis occupies a special place in this development, whereby, to put it simply, composition of sound has tended to take the place of compositions with sound. From the 1950s onwards, with instrumental works such as Le Sacrifice (1953), Metastaseis (1953-1954), and Pithoprakta (1955-1956), and electroacoustic pieces such as Diamorphoses (1957) and Concret PH (1958), he developed a conception of music focused on sound.