The world has long admired the depth and richness of Hasidism, the mystic tradition in Judaism based on the extraordinary texts of the Kaballah and the legacy of revered and charismatic teachers. Far less attention has been paid to its Rabbinical opponents, the Mithnagdim, whose teachings have been overshadowed by Hasadism's success. No less pious or inspired, the Mithnagdim argued passionately that Hasidism's emphasis on religious ecstasy risked eclipsing the Talmud and destroying the ancient tradition of its careful study. The quarrel lasted centuries and still continues - and the stakes remain enormous. Allan Nadler's new book is the first study of the theological roots of the Mithnagdic objection to Hasidism. His pioneering effort fills the void in scholarship on Mithnagdic thought and corrects the impression that there were no compelling theological alternatives to Hasidism during the period of its rapid spread across Eastern Europe at the turn of the 19th century. Nadler recovers the work of Rabbi Elijah of Vilna, Phinehas of Polotsk and other figures who established Mithnagdism as an influential movement in Jewish religious thought. Their extensive writings on religious ethics, philosophy and exegesis make it clear that the Mithnagdim were much more than negative, narrow critics of Hasidism. In Nadler's account, Mithnagdism emerges as a highly developed religious outlook that is essentially conservative, deeply dualistic and profoundly pessimistic about humanity's spiritual potential - all in stark contrast to Hasidism's optimism and aggressive encouragement of mysticism and religious rapture among its followers.