Astruc of Lunel (born 1250?, Lunel, near Montpellier, France—died after 1306) was an anti-rationalist Jewish zealot who incited Rabbi Solomon ben Abraham Adret of Barcelona, the most powerful rabbi of his time, to restrict the study of science and philosophy, thereby nearly creating a schism in the Jewish community of Europe.

Although Astruc revered Maimonides, who had attempted to reconcile Aristotle’s philosophy with Judaism, he deplored what he considered the excesses of Maimonides’ followers, who, he believed, undermined the Jewish faith by interpreting the Bible allegorically. They even seemed to take as a religious guide Aristotle himself, whose teachings were often said by the anti-Aristotelians to be “a jar of honey about which a dragon is wrapped.”

In a series of letters, Astruc persuaded Rabbi Adret to issue a ban in 1305 forbidding, on pain of excommunication, the study or teaching of science and philosophy by those under the age of 25. This ban provoked a counterban by other Jewish leaders against those who followed Adret’s proscription. A threatened schism among the Jewish communities of France and Spain was averted only in 1306, when Philip IV expelled the Jews from France. Astruc then settled in Perpignan, the mainland capital of the kingdom of Majorca, and vanished from view. But he published his correspondence with Rabbi Adret, which primarily concerned the restrictions on studies. Minḥat qenaot (“Meal Offering of Jealousy”), as the collected correspondence is entitled, reveals much of the religious and philosophical conflicts of Judaism in that era. The epithet ha-Yareaḥ is derived from his polemical work Sefer ha-yareaḥ (“The Book of the Moon”), the title of which refers to the town of Lunel (French lune, meaning “moon”).