Thomas Aquinas, the "Angelic Doctor," is the philosopher-theologian who did more than anyone to reconcile Christian revelation with the philosophy of Aristotle, whose works were flooding back into the Latin West in his day and were regarded by many as a threat to the faith. Against those who would have banned Aristotle, Aquinas argued that reason and revelation, rightly understood, cannot conflict, because both come from God: reason can establish some truths (that God exists, for instance) on its own, while others (the Trinity, the Incarnation) are known only by revelation, and the two form a single coherent order. His vast Summa Theologiae, structured as a series of disputed questions with objections and replies, sought to lay out the whole of Christian doctrine on this basis, including the "Five Ways," his arguments for God's existence from motion, causation, contingency, degree, and design. Though controversial in his own century, some of his positions were condemned shortly after his death, his thought was gradually recognized as authoritative, and Thomism became, especially after the nineteenth century, something close to the official philosophical framework of the Catholic Church. He is the enduring model of the conviction that faith seeks, and is compatible with, rigorous rational understanding.