Book excerpt: You can't judge a book by its cover...but some covers simply speak for themselves. The most influential book jacket designs from throughout the 20th century are on display, and the fascinating images track their evolution from throwaway utilitarian "dust jackets" into a powerful modern art form. Three hundred hardcover and paperback book jackets appear in full color, including many from rare first editions seldom seen outside a serious collector's library. Accompanying analysis commemorates the contributions of top European and American artists like Victor Gollancz, Paul Rand, and Barnett Freedman; explains how cover art styles helped launch such publishing brands as Penguin and Bloomsbury; and explores the impact of today's digitally designed covers.