The film develops around a series of shots of Gino Marotta's sculptures at the Natural-Artificial exhibition at the Galleria dell'Ariete (Milan, 1968). The images are inserted in a tight montage that alternates natural visions with pure ghosts of shapes-light in motion. The rhythms are marked by the music of Cage. Shapes and colors outline volumes like liquid and bright substances, derived from the intense play of transparencies and overlaps. From a manuscript note preserved in the Marinella Pirelli Archive (Varese), the artist reports: Marotta's sculptures were the pretext I was looking for: they are in methacrylate perspex, transparent and polarizing, with those surfaces made of pure luminous variations: but they were precisely a pretext.