At first the Pope, Leo X., took little heed of the disturbance; he is reported even to have said, when he heard of it, that "Friar Martin was a man of genius, and that he did not wish to have him molested." Some of the cardinals, however, saw the real character of the movement, which gradually assumed a seriousness evident even to the Pope; and Luther received a summons to appear at Rome, and answer for his theses (1518). Once again in Rome, it is unlikely he would ever have been allowed to return. His university and the elector interfered, and a legate was sent to Germany to hear and determine the case. Cardinal Cajetan was the legate, and he was but little fitted to deal with Luther. He would enter into no argument with him, but merely called upon him to retract. Luther refused, and fled from Augsburg, whither he had gone to meet the papal representative. The task of negotiation was then undertaken by Miltitz, a German, who was envoy of the Pope to the Saxon court, and by his greater address, a temporary peace was obtained. This did not last long. The reformer was too deeply moved to keep silent. "God hurries and drives me," he said; "I am not master of myself; I wish to be quiet, and am hurried into the midst of tumults." Dr. Eck and he held a memorable disputation at Leipsic (1519), in which the subject of argument was no longer merely the question of indulgences, but the general power of the Pope. The disputation, of course, came to no practical result; each controversialist claimed the victory, and Luther in the meantime made progress in freedom of opinion, and attacked the papal system as a whole more boldly. Erasmus and Hutten joined in the conflict, which waxed more loud and threatening. In 1520 the reformer published his famous address to the "Christian Nobles of Germany." This was followed in the same year by a treatise "On the Babylonish Captivity of the Church." In these works, both of which circulated widely and powerfully influenced many minds, Luther took firmer and broader ground; he attacked not only the abuses of the papacy and its pretensions to supremacy, but also the doctrinal system of the Church of Rome. "These works," Ranke says, "contain the kernel of the whole Reformation." The papal bull containing forty-one theses was issued against him; the dread document, with other papal books, was burned before an assembled multitude of doctors, students, and citizens, at the Elster Gate of Wittenberg. Germany was convulsed with excitement. Eck (who had been the chief agent in obtaining the bull) fled from place to place, glad to escape with his life, and Luther was everywhere the hero of the hour.