The philosophical movement in mediæval Jewry was the result of the desire and the necessity, felt by the leaders of Jewish thought, of reconciling two apparently independent sources of truth. In the middle ages, among Jews as well as among Christians and Mohammedans, the two sources of knowledge or truth which were clearly present to the minds of thinking people, each claiming recognition, were religious opinions as embodied in revealed documents on the one hand, and philosophical and scientific judgments and arguments, the results of independent rational reflection, on the other. Revelation and reason, religion and philosophy, faith and knowledge, authority and independent reflection are the various expressions for the dualism in mediæval thought, which the philosophers and theologians of the time endeavored to reduce to a monism or a unity.