Why are the paleolithic Venus of Willendorf, Michelangelo's Sistine Chapel frescoes, and Marcel Duchamp's ready-made urinal all considered works of art? Why, strictly speaking, is a Cindy Sherman photograph more art-like than a Da Vinci portrait? How did the painters and sculptors of the Renaissance see their creations? And who decides what art is today? In the tradition of Marshall McLuhan and John Berger, this learned and deliciously subversive...