Arthur C. Danto is Johnsonian Professor of Philosophy Emeritus at Columbia University. He is art critic for "The Nation "and the author of more than twenty books, including "Playing with the Edge: The Photographic Achievement of Robert Mapplethorpe "(California, 1996), "Encounters and Reflections: Art in the Historical Present "(California, 1995), and, now in paperback, "Beyond the Brillo Box: The Visual Arts in Post-Historical Perspective "(California, 1998).