Book excerpt: Compellingly and authoritatively written, this biography illuminates the dilemmas that Europe’s Jews have faced over the past century. The discussion of the inner struggles of one of twentieth-century Judaism’s most enigmatic religious leaders—a figure who became a central ideologue of modern Orthodoxy despite his traditional training in a Lithuanian yeshiva—elucidates many institutional and intellectual phenomena of the Jewish world, and especially in pre-war Europe, that have so far received little attention.