Moses ben Maimon (1138–1204) was born in Córdoba and fled with his family from the Almohad pressure to convert: first to Morocco, then Palestine, finally Cairo. He served as chief physician at the court of Saladin and led Egypt's Jewish community. His Mishneh Torah systematised the whole corpus of rabbinic law into a coherent handbook.

His great philosophical work, the Dalalat al-Ha'irin (Guide for the Perplexed, c. 1190), was written in Arabic and quickly translated into Hebrew and Latin. The book addresses a Jew who has acquired scientific or philosophical knowledge and faces apparent conflict with Torah passages that seem to violate reason (God's 'hand', 'eye', 'wrath'). Maimonides' answer is twofold. First, these anthropomorphic expressions are allegorical; the correct way to speak of God is by 'negative theology' — saying what He is not. Second, Aristotle's metaphysics is largely correct, but on the creation of the world reason must yield to revelation.

The Guide provoked a storm in its own century. Many rabbis charged it with heresy and demanded its burning; within a hundred years, however, it had become one of the central reference texts of rabbinic thought. Its Latin translation reached Aquinas in the 13th century, who cites Maimonides directly as 'Rabbi Moyses'. The Guide is one of the rare points at which Jewish, Islamic, and Christian medieval philosophy meet on the same page.