[68] enchained in the prison which Christianity had built around the human mind. It was not indeed inactive, but its activity took the form of heresy; or, to pursue the metaphor, those who broke chains were unable for the most part to scale the walls of the prison; their freedom extended only so far as to arrive at beliefs, which, like orthodoxy itself, were based on Christian mythology. There were some exceptions to the rule. At the end of the twelfth century a stimulus from another world began to make itself felt. The philosophy of Aristotle became known to learned men in Western Christendom; their teachers were Jews and Mohammedans. Among the Mohammedans there was a certain amount of free thought, provoked by their knowledge of ancient Greek speculation. The works of the freethinker Averroes (twelfth century) which were based on Aristotle’s philosophy, propagated a small wave of rationalism in Christian countries. Averroes held the eternity of matter and denied the immortality of the soul; his general view may be described as pantheism. But he sought to avoid difficulties with the orthodox authorities of Islam by laying down the doctrine of double truth, that is the coexistence of two independent and contradictory truths, the one philosophical, and the other religious. This [69] did not save him from being banished from the court of the Spanish caliph. In the University of Paris his teaching produced a school of freethinkers who held that the Creation, the resurrection of the body, and other essential dogmas, might be true from the standpoint of religion but are false from the standpoint of reason. To a plain mind this seems much as if one said that the doctrine of immortality is true on Sundays but not on week-days, or that the Apostles’ Creed is false in the drawing-room and true in the kitchen. This dangerous movement was crushed, and the saving principle of double truth condemned, by Pope John XXI. The spread of Averroistic and similar speculations called forth the Theology of Thomas, of Aquino in South Italy (died 1274), a most subtle thinker, whose mind had a natural turn for scepticism. He enlisted Aristotle, hitherto the guide of infidelity, on the side of orthodoxy, and constructed an ingenious Christian philosophy which is still authoritative in the Roman Church. But Aristotle and reason are dangerous allies for faith, and the treatise of Thomas is perhaps more calculated to unsettle a believing mind by the doubts which it powerfully states than to quiet the scruples of a doubter by its solutions. There must always have been some private