Sa‘d ibn Mansūr Ibn Kammūna was a Jewish physician-philosopher of Iraqi origin who flourished in the thirteenth century (d. 1284). Best known for his original and comparative inquiry into the three monotheistic faiths, whose publication nearly cost him his life, he was, in fact, a very productive thinker, and a scholar well in tune with developments in the philosophy and science of his day. He had personal contact with some leading intellectuals, and he played an important role in the diffusion of some new trends of thought. His legacy, in the form of commentaries, correspondence, and original works, is now being studied in earnest.