“Tell a dream, lose a reader,” the saying goes, but Brad Watson ignored that advice in his splendidly dream-laden novel, The Heaven of Mercury, and watched it become a finalist for the National Book Award in 2002. Watson’s dreams work because they avoid twee mysticism or kitsch — they’re made of reality with a slight shift, as if his characters phase just out of the earthly plane, then return with visions that seem logical, essential to our understanding of the story.