it's an excerpt from Don Dellilo's novel Underground. The full paragraph is:
"He crouched under the great split sky, ears set low and his head sloped. The sky was divided, split diagonally, a flat blue, a soft slatey blue, like the head of a crested jay, and a yellow that wasn't even yellow, an enormous heartbreak yellow sweeping to the east, a smoky goldshot stain, and the kids with the knotted arms fell down in a row."