The first comprehensive look at Rauschenberg's Cardboard series, a previously unexplored realm of the artist's oeuvre Robert Rauschenberg (b. 1925) began to investigate the boundaries between painting and sculpture in the 1950s, working with a variety of found objects in his Combine paintings and freestanding Combines. Later, in his Cardboard series (1971-72), he confined himself to the use of cardboard boxes, eliminating virtually...