Cy Twombly‘s Treatise on the Veil (Second Version) is considered a pivotal work in the career of one of the most important artists to emerge in the wake of Abstract Expressionism. Yet, due to its size—close to thirty-three feet in length—this highlight of his celebrated “grey-ground” period is rarely shown and has not been exhibited in New York in nearly thirty years. Beginning September 26, Treatise on the Veil and a selection of related drawings will go on view at the Morgan Library & Museum, in a collaboration with Houston’s Menil Collection, which owns the works and organized the exhibition. The show will run through January 25, 2015.