Rabbeinu Gershom, Light of the Exile, and the Ban on Polygamy

By the early eleventh century the centre of the Jewish world had begun shifting from Babylonia to the Rhine. In Mainz, Worms and Speyer grew the communities soon called Ashkenaz, and their teacher was Rabbeinu Gershom ben Yehudah, named Me'or HaGolah, 'Light of the Exile.' His yeshiva drew students from all Germany and France; he established a reliable text of the Talmud and wrote the first Ashkenazi commentaries, still printed in standard editions under his name.

He is remembered above all for his takkanot, enactments backed by the ban of excommunication. First: no man may have more than one wife. The Torah had not forbidden polygamy, and it still occurred in the Muslim East, but in Christian Europe Rabbeinu Gershom ended it so decisively that it came to feel like Jewish norm itself. Second: a man may not divorce his wife against her will. Third, strikingly modern: one may not open and read another's letter. Fourth: no one may reproach a returning Jew for having been baptised under force.

His own son was forcibly baptised and died before returning; the father mourned him the full days of mourning. His penitential poems are still recited in the Days of Awe.