During the early 1960s, following his first showing at the New York gallery of Leo Castelli (1907 - 99), he began to include more colour in his painting, together with numerous classical references (Leda and the Swan, the Birth of Venus) and
scatological imagery, a process which peaked in the «Ferragosto paintings», as well as his series entitled «Nine Discourses on Commodus» (1963), a portrait of the power - crazy Roman emperor created under the influence of works by Francis Bacon (1909 - 93).