HASIDISM, arguably the most vibrant religious movement in the history of modern Jewry, was born in eighteenth-century Poland with the teachings of Rabbi Israel Ba'al Shem Tov (Master of the Good Name, or, better, Good Master of the Name). Emphasizing the centrality of joy in the service of God, the crucial role of prayer, and the opportunity to cleave to the divine through a tzaddik, or rebbe—a charismatic leader seen as a conduit between the heavenly and earthly realms—the Ba'al Shem Tov and his successors fashioned a message that energized and redirected Jewish piety, ritual, and social institutions. The Chabad stream originated in the career of Rabbi Shneur Zalman (1745–1813), originally of Liozna, later of Lyady, a towering figure expert in Jewish law and mysticism who infused a movement marked by pietistic enthusiasm with a strongly intellectual component. Indeed, the term Chabad itself is an acronym for the Hebrew words, ḥokhmah, binah, da'at (wisdom, understanding, knowledge) as used in Jewish mysticism. A host of factors rendered hasidism highly controversial, and the Chabad group, centred in Lithuania, found itself at the vortex of a campaign spearheaded by the Vilna Gaon (Rabbi Elijah ben Solomon Zalman, 1720–97), the greatest talmudist of his and all subsequent generations and the driving force behind a series of bans against nascent hasidism in the 1770s and thereafter.

With the dawn of the next century, hasidim did more than weather these attacks. As a multitude of rebbes founded proliferating dynasties in towns and hamlets throughout the Jewish Pale of Settlement, the movement spread through eastern Europe and became the dominant form of Judaism in much of the heartland of nineteenth-century Jewry. Opponents (mitnagedim, or, in the pronunciation that prevailed among these Jews, ‘misnagdim’) did not entirely abandon the cause, but opposition waned in the face of new social and religious realities.

First, it became very difficult to delegitimate a movement that commanded the allegiance of so many observant Jews. Second, the radicalism of early hasidism diminished as it was transformed from a movement of rebellion against the Jewish communal establishment into an established order of its own.