Twombly describes a series of paintings he has just finished and how Castelli should hang them in the gallery. Date based on the assumption that the series Twombly refers to is his Nine discourses on Commodus, painted in 1963.
Cy Twombly letter to Leo Castelli, 1963?. Leo Castelli Gallery records, circa 1880-2000, bulk 1957-1999. Archives of American Art, Smithsonian Institution.
Current copyright status is undetermined
Archives of American Art, Smithsonian Institution Washington, D.C. 20560