Maimonides"s Mishneh Torah is considered by traditionalist Jews even today as one of the chief authoritative codifications of Jewish law and ethics. It is exceptional for its logical construction, concise and clear expression and extraordinary learning, so that it became a standard against which other later codifications were often measured. It is still closely studied in rabbinic yeshivot (academies). A popular medieval saying that also served as his epitaph states, From Mosheh (of the Torah) to Mosheh (Maimonides) there was none like Mosheh. It chiefly referred to his rabbinic writings. But Maimonides was also one of the most influential figures in medieval Jewish philosophy. His brilliant adaptation of Aristotelian thought to Biblical faith deeply impressed later Jewish thinkers, and had an unexpected immediate historical impact. Some more acculturated Jews in the century that followed his death, particularly in Spain, sought to apply Maimonides"s Aristotelianism in ways that...