Ours is the age of the picture. Pictures abound in our newspapers and magazines, in storybooks and on the glossy pages of instruction manuals. We find them on billboards and postage stamps, on the television screen and in the cinema. And in all of these cases pictures inform us: they explain, they clarify, they elucidate - and at times, too, they entertain and delight us. Images on the television screen have all but replaced the printed word as a source of information about the world; and nowadays, too, picture books and comic strips are consulted much more readily, and with much less...