Andy Warhol lifted the sheet of acetate to the light, and for a moment, he and Marilyn Monroe dissolved into the same image. It was early 1964 in the Silver Factory, and the photographer William John Kennedy had asked Warhol what the large roll leaning against the wall was for. "These are the acetates used in my silkscreens," Warhol replied, and with a flurry of movement, held one sheet up. Through Marilyn's face, the artist peered out at the camera; Kennedy pressed the shutter.