In Paris in the 1890s, Eugène Frey was a young painter who rapidly steered his career towards the shadow theatres and magic lanterns that animated cabaret stages. In 1900 he developed the technique for Décors lumineux à transformations: Light Set transformations, a complex system of lighting projections combining pictorial, photographic and cinematographic techniques that allowed stage sets to be dressed in multiple variations of colours, lights and forms, while also incorporating moving images. He developed this unique process on the stage of the Opéra de Monte-Carlo between 1904 and 1938. The artist João Maria Gusmão conceived this very first monograph devoted to Eugène Frey, by reinterpreting the Light Set technique that was contemporary to the origins of cinema. Published to accompany the exhibition organised by the Nouveau Musée National de Monaco at the Villa Paloma, the book brings together Frey’s theatrical creations with those of numerous other inventors from the first half of the 20th century.