For sheer unpredictable brilliance, Gogol may come to mind, but no author alive today takes a reader as far as Helen DeWitt into the funniest, most yonder dimensions of possibility. Her jumping-off points might be statistics, romance, the art world's piranha tank, games of chance and games of skill, the travails of publishing, or success. "Look," a character begins to explain, laying out some gambit reasonably enough, even if facing a world of boomeranging...