Best known for cheeky conceptual works--like his signed urinals ("R. Mutt") and his graffitioed Mona Lisa--Marcel Duchamp (1887-1968) was also an extraordinary painter and sculptor (Nude Descending a Staircase) who changed the language of twentieth-century art and reigns with Picasso and Matisse as one of its greatest influences. Joseph Masheck has compiled a sampler of the best writing on Duchamp, with pieces that include Duchamp's obituary from Artforum, written by Jasper Johns; Octavio Paz on the ready-mades; a Duchamp post-mortem by Hans Richter; Donald Judd's investigation...