Isaac ben Judah of Mainz

Isaac ben Judah of Mainz, Germany, led the famous yeshiva founded by Rabbenu Gershom (ca. 960–1040). He was a student of Eliezer ben Isaac ha-Gadol (d. 1060), who had also headed the Mainz yeshiva. Little is known about Isaac’s life other than the fact that he was one of the teachers of Rashi (1040–1105). Isaac’s students referred to him as moreh tsedek (righteous teacher). Dozens of his responsa survive, many of which were addressed to Rashi. He probably also participated in writing the talmudic commentary ascribed to Rabbenu Gershom.