Isidore Isou was a Romanian-born French poet, dramaturge, visual artist, and film director: a prominent member of the avant-garde. Given his Jewish origins and the repressive regime of Ion Antonescu in Romania, Isou fled to Paris near the end of World War II. Here, he began working as a journalist, co-founding Da, an underground magazine published in collaboration with Serge Moscovici. With his friend and collaborator Gabriel Pommerand, Isou co-founded Lettrism, a literary and artistic movement based on the sign, advocating the destruction of words in favor of letters. In 1946, Isou organized his first Lettrist manifestation in Paris, stating that Dada had died and that Lettrism had taken its place. The following year, he published Introduction à une nouvelle poésie et à une nouvelle musique, containing the first manifesto of Lettrist poetry. The Lettrist poem consists of a text script for a vocal performance composed of meaningless sounds transcribed through letters. On the visual side, it is presented using all possible means of notation: graphic, stenographic, cryptographic, algebraic, numerical, and musical. In 1951, Isou’s Traité de bave et d’éternité was screened at the Cannes Film Festival. The film, composed of wrecked and discordant images, blank frames, inflammatory monologues, and onomatopoeic poems—defined by Jean Cocteau as “the most beautiful scandal”—shocked the audience. During the same period, Maurice Lemaître, Gil J. Wolman, and Françoise Dufrêne joined the Lettrist group, followed by Jacques Spacagna, Roberto Altmann, and Gérard-Philippe Broutin. A compulsive writer, Isou drafted hundreds of works concerned not only with the visual arts but also with economics, mathematics, sociology, and psychology. Eroticism and hedonism are the themes of Initiation à la Haute Volupté, initially published as a book in 1960 and reissued as a series of silkscreens by Edizioni Conz in 1989. In 1987, Isou participated in documenta 8 in Kassel. Isou’s work and the history of Lettrism are the focus of numerous publications. His works are included in the collections of the Museo Reina Sofía in Madrid, the MACBA – Museu d’Art Contemporani de Barcelona, and the Centre Pompidou in Paris, where a major retrospective took place in 2019.