The rise of the exhibition as critical form and artistic medium, from Robert Smithson's antimodernist non-sites in 1968 to today's institutional gravitation toward the participatory. In 1968, Robert Smithson reacted to Michael Fried's influential essay "Art and Objecthood" with a series of works called non-sites. While Fried described the spectator's connection with a work of art as a momentary visual engagement, Smithson's non-sites asked...