This in-depth exploration of celebrated French artist François Morellet (1926-2016) showcases his diverse oeuvre, famous for infusing systematic and rigorous experimentation with humor and playfulness. Morellet's interest in kinetic and optical effects spurred work that engages viewers' perception and participation, ensuring an element of chance within his predetermined systems and challenging the convention of the artistic genius. This book features new scholarship by an international group of renowned art historians and curators. Essays explore topics such as the conceptual stakes of Morellet's practice, the influence of Brazilian geometric abstraction and the Islamic decorative tradition, and the role of humor in his work. Also included is an extensive selection of previously untranslated writings by the artist himself. With striking new photography of the artworks--such as Morellet's geometric paintings, neon works, and architectural interventions--this is the definitive book on a fascinating, multifaceted artist.