Gershom Scholem stands out among modern thinkers for the richness and power of his historical imagination. A work widely esteemed as his magnum opus, Sabbatai Ṣevi offers a vividly detailed account of the only messianic movement ever to engulf the entire Jewish world. Sabbatai Ṣevi was an obscure kabbalist rabbi of seventeenth-century Turkey who aroused a fervent following that spread over the Jewish world after he declared himself to be the Messiah. The movement suffered a severe blow when Ṣevi was forced to convert to Islam, but a clandestine sect survived. A...