The greatest Jewish philosopher of the medieval world, Maimonides was born in Cordoba in Spain and educated in rabbinical and biblical studies as well as philosophy and science. With the conquest of Cordoba by the Almohads in 1148 the family fled to North Africa, to Palestine, and finally settled in Egypt. He supported himself as a physician, and became the revered head of the Egyptian Jews. Maimonides wrote extensively and authoritatively on Jewish law, but as a philosopher is remembered primarily for his Guide for the Perplexed, first written in Arabic and subsequently translated into Hebrew and Latin. In keeping with the rabbinical doctrine that certain matters are reserved for the select few, Maimonides' work has an enigmatic form, and has been intepreted in various ways. It is a guide for those who believe in the Law but are perplexed by the meaning of various biblical terms. This leads Maimonides to a discussion of the nature of divine attributes. He holds with Avicenna a distinction between existence and essence, but adds the distinctive doctrine that no positive essence may be attributed to God, who is therefore known only by negation. However, he goes on to establish the existence, unity, and incorporeal nature of God, and proves his existence by standard physico-theological arguments (he appears to have held that Avicenna's cosmological argument was a physical argument).