When beginning a new piece, the American artist Charles Ray, born in Chicago in 1953, asks himself one question: What is sculpture? Ray works slowly, and his full creative output counts about 100 pieces. But his in-depth knowledge of Ancient Greek sculpture and his unsettling approach to the classic nude have made his work unique. Critics and viewers alike describe Ray’s creations as jarring, strange, enigmatic, and immediate. Spanning both the Bourse de Commerce and the Centre Pompidou, this is Ray’s first big retrospective in France. —E.C.