The Guide for the Perplexed by Moses Maimonides

According to Wikipedia, The Guide for the Perplexed is one of the major works of Rabbi Moshe ben Maimon, better known as Maimonides or the Rambam. It was written in the 12th century in the form of a three-volume letter to his student, Rabbi Joseph ben Judah of Ceuta, the son of Rabbi Judah, and is the main source of the Rambams philosophical views, as opposed to his opinions on Jewish law... Moses Maimonides (March 30, 1135 Cordoba, Spain ? December 13, 1204 Fostat, Egypt), was a rabbi, physician, and philosopher in Andalusia, Morocco and Egypt during the Middle Ages. He was one of the various medieval Jewish philosophers who also influenced the non-Jewish world. Although his copious works on Jewish law and ethics were initially met with opposition during his lifetime, he was posthumously acknowledged to be one of the foremost rabbinical arbiters and philosophers in Jewish history. Today, his works and his views are considered a cornerstone of Jewish thought and study.