At Wartburg he began that course of interference with political administration and ecclesiastical organization which made his later years as a reformer so different from his earlier, and in the end led him to the practical denial of nearly every principle that he had affirmed. His own protection by the Elector Frederick against the combined power of pope and emperor made clear to him, he thought, the method by which a reformation might be attempted. While at Wartburg he thought out and wrote what he entitled, “Warning to all Christians to Abstain from Rebellion and Sedition,” in which he maintained the principle from which he never thereafter departed, that the civil Rulers had both the right and the duty to undertake the reformation of the church, and that any other principle was impracticable and dangerous. That there be no mistaking his meaning I give his words: Therefore have regard to the rulers. So long as they undertake nothing and give no command, keep quiet with hand, mouth and heart, and undertake nothing. If you can persuade rulers to undertake and command, you may do it. If they will not you should not. But if you proceed, you are wrong and much worse than the other party. This no doubt was called forth by the news of the proceedings at Wittenberg. For even with Luther away, Wittenberg, with its growing, aggressive university, was the center of the Reformation. New thoughts had been put into men’s minds, new aspirations, new purposes had come into their hearts. Luther had long before preached that the mass was wrong, but had gone right along celebrating it, and so had he taught about other things, but continued to practice them. His teaching had taken deep root, and Zwilling, chaplain of the Augustinian convent, a bold, zealous and eloquent man, who had the confidence of the people, declared that the mass ought to be abolished and that it was a sin to celebrate it. “The members of the convent, the prior excepted, agreed with him. The prior asserted his authority; the monks rebelled; the elector interfered and referred the case to the university. The university decided in favor of Zwilling and the monks, Melanchthon writing the opinion.” He attacked earnestly and bitterly monastic vows, celibacy, clerical garb, the use of images and pictures in the churches. His teaching strongly implied that liberty could not be attained till all these things were swept away.