ISSERLES, MOSHEH (c. 1520–c. 1572), known by the acronym RaMa (Rabbi Mosheh), was a Polish rabbi, halakhist, and scholar. Isserles was born in Kraków to one of the most powerful families of the Jewish community of sixteenth-century Poland and rose very rapidly to a position of prominence in the rabbinical world of Ashkenazic Jewry. Isserles's wealth and social status, as well as his ties by marriage to other prominent intellectual and communal figures in Polish Jewry, allowed him to wield substantial authority at a young age, primarily through the important yeshivah that he established in Kraków. His contributions to Jewish law and learning were vastly influential, and he was one of the few eastern European rabbis of his age to be venerated as a saintly leader for centuries after his death.

Isserles was trained in the Talmudic academy of Shalom Shakhna of Lublin, where he...