Anti-sacerdotalism led Wycliffe later on to attack a doctrine to which the clergy owed much of their hold upon the popular mind, whence largely came the peculiar veneration in which they were held—the doctrine of Transubstantiation. The miracle of the mass obtained a special note of awesome mystery from that doctrine; and to the ignorant or superstitious mind it was natural to regard those who by the simple pronunciation of the prayer of consecration could transform bread and wine into the body and blood of the Blessed Lord as miracle-workers. For the orthodox philosophy of Wycliffe’s day, Nominalism, there was little difficulty in believing in such a transformation. Wycliffe was a realist, and to him the nominalist position seemed untenable altogether. In the days of Abelard, and again in those of Thomas Aquinas, Realism had been the orthodox philosophy, and Aquinas in demonstrating that the abstract and general truths of Christianity were acceptable to the reason did the Church of his day a great service. But another realist had come after him, who had most trenchantly attacked St. Thomas, destroying all the reasonableness of the great Doctor’s philosophic structure, and emphatically ousting the reason and substituting the authority of the Church as the only sure guide in the sacred mysteries of religion, the only sure foundation of faith. There were action and reaction in the abstract thought of the Middle Ages, as indeed there have ever been in history. The reaction against the Realism of St. Thomas, apparent in Duns Scotus, grew intenser when the principles of Ockham became the popular, and were recognized as the orthodox, principles of Christian theology. It could easily be shown that Realism was apt to lead to exaggerations either heretical or absurd, very apt to end in Pantheism.[153] The fact of the matter was that either school of the scholastic philosophy might be productive of heresy, by laying especial emphasis on one particular aspect of truth to the exclusion of others; that different generations, changing subtly in mental outlook and spiritual temperament, are susceptible to different phases of truth. It is not a matter of Yea or Nay, but simply a varying stress of mode or fashion. But we do not look for recognition of such a fact on the part of any mediæval controversialist. There are no half lights and compromises with them; they have each his own vision of truth, and bitterly assail their opponents as enemies of the light.