Maimonides, the renowned Jewish theologian and physician, also wrote on the relationship between Judaism and the sciences, astronomy in particular. He spent his formative years in Spain and North Africa. He eventually settled in Fusṭāṭ. In his youth, regarding matters of cosmography (which were later to be a major concern), he sought out the son of Jābir ibn Aflaḥ as well as some pupils of Ibn Bājja. Maimonides prepared corrected versions of texts written by Jābir and Ibn Hūd, ruler of Seville. Astronomical issues are stressed at several places in Maimonides’ Guide of the Perplexed; the most detailed discussion is found in part 2, chapter 24. Maimonides’ contribution to mathematical astronomy is his procedure for determining the visibility of the lunar crescent, which takes up several chapters of his great law code, the Mishneh Torah. [see BEA, Langermann]; GAS V.141