"Duchamp brothers and sister" was the designation bestowed upon this original family—as if an avant-garde corporation—which included the painters Jacques Villon and Suzanne Duchamp, the sculptor Raymond Duchamp-Villon and that master of objective humor, Marcel Duchamp. After studying at the Académie Julian, Marcel completed most of his paintings between 1911 and 1912, trying out various experiments and "taking stock of painting in eight months": a Cubist canvas, Les Joueurs d'échecs was followed by a "mechanomorphic" canvas, Moulin à café, then a Futurist canvas, Nu descendant un escalier. Duchamp compared the act of painting to an intellectual exercise: "Painting should not be exclusively visual or retinal. It must also engage the gray matter, our appetite for comprehension." Searching for new possibilities of expression, in 1914 he invented the "readymade," an everyday object taken out of its habitual context, and the mechanical "optical machine," He also executed a huge glass panel, La Mariée mise à nu par ses célibataires, même (1915-23), preparing it with plans and graphs. In 1915 Duchamp traveled to the United States and became a member of the Comité des Indépendants in New York, resigning when the Comité refused the readymade urinal he wanted to exhibit under the title Fountain (1917). Publishing ephemeral reviews—The Blind Man, Rongwrong, New York Dada—he contributed to the propagation of a super-Dadaism, giving it a frigid, haughty tone. He returned to France for a time, and witnessed the birth of surrealism. Giving up painting for good in 1928, he was content to coin Puns attributed to his alter-ego, Rrose Sélavy, create "rotoreliefs," which he presented at the Concours Lépine (the annual inventors' fair) in 1935, along with anti-utilitarian objects that defied reality. When Duchamp paid his dentist with an exorbitant hand-drawn check, or invented a winning formula to break the bank of the Monte Carlo roulette, he was phlegmatically embodying surrealism's art de vivre. The surrealists unanimously elected him their supreme arbiter, accomplice and inspirer of novelty, admiring his nonchalance and sense of irony. In 1937 he held his first solo show at the Arts Club in Chicago. Just as he had published his texts La Mariée in La Boîte Verte (1934), he brought together his complete works in a "portable museum" in the shape of a suitcase, the Boîte-en-Valise (1935-41), in an edition of 300 copies, and the unpublished notes of his youth in La Boîte Blanche (1966), titled À l'infinitif. An entire section of the Philadelphia Museum of Art is devoted to Duchamp, where one can view his last creation, Étant donnés: 1° La chute d'eau; 2° Le gaz d'éclairage, a landscape behind a closed wooden door, viewable through a knothole at eye level, in which one sees a nude woman reclining on a woodpile, holding a lit Welsbach burner. Is she a rape victim, a streetwalker, or a nude stroller who took a spill? It is up to each of us to decide according to our mood, as Duchamp's supreme lesson is the demonstration that the meaning of a thing observed depends only on its beholder.