At the back of a dimly lit room at the north-east wing of the Philadelphia Museum of Art the visitor may, or may not, discover an old, weathered Spanish door. Approaching this unlikely sight, a concealed view behind the door becomes noticeable as a result of light emanating from two peepholes. The act of looking through them transforms the unsuspected viewer into a voyeur and reveals a brightly lit three-dimensional diorama: a recumbent, faceless, female nude, holding a gas lamp and bathed in light is submerged in twigs in an open landscape where a waterfall silently glitters [1a, 1b]. The explicit pornographic pose of the splayed legs and the exposed pudenda is dazzling. On careful inspection, this startling view is only possible through another intersecting surface; between the viewer and the nude stands a brick wall on which an irregular rupture has been opened – as if by a violent collision – making the scene even more unsettling. Defying traditional definitions of painting or sculpture Marcel Duchamp's enigmatic final work is a carefully constructed assemblage of elements, with an equally enigmatic title: Etant Donnés: 1°la chute d'eau, 2°le gaz d'éclairage… (Given: 1st the Waterfall, 2nd the Illuminating Gas…), 1946–1966.