The Semag

Rabbi Moshe of Coucy (c. 1200–1260), known as the Semag (Sefer Mitzvot Gadol, 'The Great Book of Commandments'), was a prominent French Tosafist and halakhic authority of the thirteenth century. Based in Coucy-le-Château in northern France, he was active during a period of intense Jewish learning in Ashkenaz. The Semag is best remembered for his systematic enumeration and explanation of the 613 mitzvot (commandments), organized by positive and negative precepts, drawing on earlier rabbinic sources and contemporary Tosafist reasoning. His work became influential across medieval Jewish communities and was widely studied alongside other mitzvot-codifications. Moshe was also known for his pietistic inclinations and concern with the spiritual dimensions of halakhah, not merely its technical aspects.