Also known as Gershom ben Judah of Mayence. An outstanding scholar of the late 10th and early 11th centuries, commentator on the Talmud, head of several academies in France and Germany. His learning earned him the title Me’or Hagolah, or “Light of the Exile.” He was recognized as the leading Jewish religious authority in Europe and his decisions on Jewish law were accepted as legally binding on all European Jews. Around the year 1000 he handed down numerous rabbinic rulings, forbidding the practice of polygamy, insisting on the consent of both parties to a divorce, prohibiting the opening of letters addressed to others, and modifying the laws relating to converts who had been forcibly baptized.