Book excerpt: Jewish religious practice has been transformed by the Kabbalists of Safed in the sixteenth century. They brought new meaning and importance to many Biblical and rabbinic commandments and created new rituals that have become central practices for Jews of all denominations. This volume describes the origins of these traditions and explains the mystical meaning of these specific practices and rituals. Some of these innovations include: Kabbalat Shabbat, inviting the Ushpizin to the Sukkah, Tikkun Leyl Shavuot, and visitation to the grave of Rabbi Simeon bar Yohai on Lag Be-Omer. This volume is written in a style accessible to the non-specialist in Kabbalah and the Jewishly knowledgeable general reader.