Sir Leon—Rabbi Yehuda ben Yitzchak of Paris רבי יהודה בן יצחק, סיר ליאון מפריז

In 1182 the king of France expelled the Jews from his domain, and the Paris community ceased to exist. Sixteen years later the same royal word called them back. A return is not only houses: someone has to begin teaching again.

That man was Rabbi Yehuda ben Yitzchak, called by French custom Sir Leon. He had studied with the Ri ha-Zaken and the Ritzva—that is, he held the Dampierre training in his hands—and he carried it to the capital. His treatment of the tractates survives: the Tosafot of Rabbi Yehuda of Paris are still learned.

His mark is not in books but in students. The yeshiva passed after him to Rabbi Yechiel of Paris—the man who, eighteen years after his teacher's death, would answer for the Talmud alone before the royal court—and the burning of some twenty cartloads of books in 1242 would be the end of the very learning Sir Leon had restored in that city. Another student, Rabbi Yitzchak, left for Vienna and wrote the Or Zarua, in which the Paris lessons are written down.