In 70 CE, the Jews were an agrarian and illiterate people living mostly in the Land of Israel and Mesopotamia. By 1492, the Jewish people had become a small group of literate urbanites specializing in crafts, trade, moneylending, and medicine in hundreds of places across the Old World, from Seville to Mangalore. What caused this radical change? This book presents a new answer to this question by applying the lens of economic analysis to the key facts of fifteen formative centuries of Jewish history. The book offers a powerful new explanation of one of the most significant transformations in Jewish history while also providing fresh insights into the growing debate about the social and economic impact of religion.