https://www.nytimes.com/1977/10/16/archives/once-established-says-jasper-johns-ideas-can-be-discarded-once.html

His ideas are apt to come from the observance of fleeting visual phenomena: In 1967, for example, while driving through Harlem, he spotted out of the corner of his eye a store with a wall painted to resemble flagstones. Later, preparing to paint it, he sent David Whitney to look for and photograph it. Whitney couldn't find it; neither could Johns when he himself went to track it down. But he claimed the image for himself—“what's interesting to me is the fact that it isn't designed, but taken. It's not mine.”