On the complex aesthetics and ontology at work in Étienne Souriau’s unique oeuvre In this concise but expansive exegesis of the philosophical aesthetics of Étienne Souriau, philosopher David Lapoujade provides a lucid introduction to many of the key concepts underpinning Souriau’s existential pluralism. Among the various modes of existence that populate a world, Souriau grants particular importance to virtual beings—the lesserexistences. Always taking the form of a sketch or an outline, the perfection of such existences lies precisely in the incompletion with which they imbue all reality. They exist with a problematizing force, posing questions and inviting the establishment of an “art” that would make them more real. And yet, for this to happen, another existence must first see them—must be capable of hearing their appeals—and must be willing to defend their right to exist.Through discussions of modern art ranging from the dispossessed characters of Kafka and Beckett to the grids of Agnes Martin and the protographies of Oscar Muñoz, Lapoujade leads the reader into a complex philosophical world, brimming with modal existences and animated by a unique conception of creative processes, where the philosopher as artist or artist as philosopher becomes an advocate, defending the right of certain realities to gain in existence. For Souriau, nothing is given in advance, everything is a work in the making: such is the instaurative practice that grounds his entire oeuvre.