Beginning with his first novel, "The Chosen," Chaim Potok has illuminated for a vast and rightly fascinated audience the little-known and frequently misunderstood milieu of those communities of very pious Jews who live their lives in contemporary America entirely within the structure and strictures of the Old World orthodoxy of their forebears. In this dense, highly ordered, exceptionally demanding world—especially in the range of its proscriptions—Mr. Potok's brooding, passionately knowledge-hungry young protagonists commonly come to grief. In the course of their growing up, they become desperate to reach outside the prescribed confines of their religious education. Most of Mr. Potok's novels end with the unusually gifted, conflicted young protagonists leaving—and, in a sense, watching themselves leave—the community that bred and nourished them, and their protracted leave-takings are freighted, as the reader imagines their lives will always be, with shadowy self-indictment. For though they remain...