For over a hundred years, the idea of the "avant-garde" has been perhaps the most important and influential force in modern culture, ruling the critical assessment of the significance of an artist or a work of art. If they have been judged to be "avant-garde," then they are worthy of consideration. But very little attempt has been made to explore why the idea of the "avant-garde" carries so much authority, or how it came to do so. What is more, the...