A good mythology needs a Genesis story. For Jasper Johns, the dawn of creation came in the late fall of 1954, and was instigated not by divine revelation but something close to it: a vision in a dream. A year out of the army, asleep in a loft in lower Manhattan, Johns closed his eyes and saw the Stars and Stripes in the dark, not fluttering, not flying over a battlefield, but on an easel—and he was there, too, painting it. It’s hard enough to remember a dream the next morning, let alone decades on, and Johns recounted his vision of himself painting a flag with slight variations in the decades that followed: he may or may not have told Robert Rauschenberg about it over breakfast. But the next day he was at work, and by the spring of 1955, he had completed the painting he had seen in his vision.