Almost unbeknownst to him, over the years, Umberto Eco has written an authentic treatise on art. A fragmentary, discontinuous, rambling, layered and, indeed, unintentional opus magnum. It brings together essays, presentations, lectures, articles and Minerva Sachets. Heterogeneous materials largely dispersed and forgotten that, now, for the first time, have been found, reorganized and reread by Vincenzo Trione.