Based on a comparative and interdisciplinary approach, this volume for the first time interprets the biography and philosophy of the German Jewish thinker Samuel Holdheim (1806-1860), shedding new light on a neglected phenomenon of nineteenth century Jewish intellectual history - the radical Reform Movement that started in Germany and culminated in the American Jewish Reform ideology. Leading scholars of modern Jewish history and thought from Germany, France, Belgium and the United States present a thorough reading of Holdheim's influential writings in the broader context of the debates within German Jewry about the modernization of Jewish identity in an age of political emancipation and cultural integration, including such controversial issues as the authority of the rabbinical tradition or the re-interpretation of the ceremonial laws.