"So many categories!" Andy Warhol would complain, in the course of his daily trawl of antique stores, galleries, auction houses and flea markets. Though best known as an artist, Warhol was also a passionate and informed collector of unlikely antiquities and offbeat Americana. "Possession Obsession" proposes that collecting was another form of artistic practice for Warhol, certainly one that provides as much insight into his interests, tastes and ideas as his art. Accompanying essays examine the how, why, and what of Warhol's collection, the all-consuming role it played in his life, the aesthetic quality and historical associations of the objects themselves, the psychological and sexual aspects of collecting, other artists' use of collecting and the relationships between collecting and mass culture. Also included are Robert Mapplethorpe's wonderful photographs of Warhol's home, for which Patti Smith provides an introduction.