This book begins by exploring the mysterious origins of an institution so familiar that most of us never wonder where it came from—the seven-day week. Jon D. Levenson then focuses on the historical development of the Jewish Sabbath and the rich range of theological and ethical meanings it has acquired over the centuries. Levenson evaluates the theory that the Hebrew word šabbāt derives from Akkadian and that the Sabbath may have begun as a day of ill omen, only later to be reinterpreted as the joyous festival that consummates the seven-day week. He explores the quasi-magical character of the number seven in ancient Near Eastern and Mediterranean compositions and examines the revealing variation of the Sabbath commandment between the two biblical versions of the Decalogue in Exodus and Deuteronomy. He also treats sabbatical law in the Second Temple and rabbinic periods, critiquing contemporary efforts to extract a spirituality from the Sabbath that is divorced from larger questions of communal identity, normative practice, and religious affirmation. Levenson concludes by discussing modern challenges to Sabbath observance and the surprising prospects for its continuation. Written by an eminent scholar in the field, this sophisticated inquiry bridges the gap between studies that explore the spiritual meaning of Jewish Sabbath observance and those that focus strictly on the history of the tradition. It will appeal to a wide audience of academics and lay readers.