Robert S. Nelson is a Distinguished Service Professor of Art History and the History of Culture, and chair of the Committee on the History of Culture at the University of Chicago. He is the editor of "Visuality before and beyond the Renaissance: Seeing as Others Saw and coeditor of "Critical Terms for Art History, second edition, the latter published by the University of Chicago Press. Margaret Olin is a professor of art history, theory, and criticism, and Visual and Critical Studies at the School of the Art Institute of Chicago. She is the author of "The Nation without Art: Examining Mode...