Book excerpt: Maristella Botticini and Zvi Eckstein show that, contrary to previous explanations, this transformation was driven not by anti-Jewish persecution and legal restrictions, but rather by changes within Judaism itself after 70 CE--most importantly, the rise of a new norm that required every Jewish male to read and study the Torah and to send his sons to school. Over the next six centuries, those Jews who found the norms of Judaism too costly to obey converted to other religions, making world Jewry shrink. Later, when urbanization and commercial expansion in the newly established Muslim Caliphates increased the demand for occupations in which literacy was an advantage, the Jews found themselves literate in a world of almost universal illiteracy. From then forward, almost all Jews entered crafts and trade, and many of them began moving in search of business opportunities, creating a worldwide Diaspora in the process.