Jasper Johns is regarded as one of the most influential artists of the 20th century, and has remained central to American art since his arrival in New York in the 1950s. With his then partner Robert Rauschenberg, Johns helped to establish a decisive new direction in the art world, termed "Neo-Dada" at the time. Johns' striking use of popular iconography, "things the mind already knows," as he put it (flags, numbers, maps), made the familiar unfamiliar--and...