Book excerpt: Marilynne Robinson's mythical world of Gilead, Iowa -- the setting of her novels Gilead, Home, and Lila, and now Jack -- and its beloved characters have illuminated and interrogated the complexities of American history, the power of our emotions, and the wonders of a sacred world. Jack is Robinson's fourth novel in this now-classic series. In it, Robinson tells the story of John Ames Boughton, the prodigal son of Gilead's Presbyterian minister, and his romance with Della Miles, a high school teacher who is also the child of a preacher. Their deeply felt, tormented, star-crossed interracial romance resonates with all the paradoxes of American life, then and now.