Persia is home to one of the few civilizations in the world that has had a continuous tradition of philosophical thought for over two and a half millennia. As Islamic theology developed in the Middle Ages, many of its schools interacted with existing Persian philosophical currents and evolved into a distinctive philosophical 'Kalam', or dogmatic theology. Among the definitive masters of both Shi'i and Sunni theologians were numerous Persians, chief among them Al-Ghazzali and Fakhr al-Din Al-Razi, who are prominently represented here. Important selections from both Shi'i and Sunni theological schools (including Mu'tazila and Ash'ariyya) are included in the volume, many of which have never before been available in translation in the West until now.