From the ninth to the fifteenth centuries Jewish thinkers living in Islamic and Christian lands philosophized about Judaism. Influenced first by Islamic theological speculation and the great philosophers of classical antiquity, and then in the late medieval period by Christian Scholasticism, Jewish philosophers and scientists reflected on the nature of language about God, the scope and limits of human understanding, the eternity or createdness of the world, prophecy and divine providence, the possibility of human freedom, and the relationship between divine and human law. Though many viewed philosophy as a dangerous threat, others incorporated it into their understanding of what it is to be a Jew. This Companion presents all the major Jewish thinkers of the period, the philosophical and non-philosophical contexts of their thought, and the interactions between Jewish and non-Jewish philosophers. It is a comprehensive introduction to a vital period of Jewish intellectual history.