This was merely a truce, and it was soon broken. Dr. Eck, one of the partisans of the Church, challenged Luther's friend and follower, Carlstadt, to a public discussion in Leipzig, and it was not long before Luther himself was compelled to take part in it. He declared his views with more clearness than ever, disregarding the outcry raised against him that he was in fellowship with the Bohemian heretics. The struggle, by this time, had affected all Germany, the middle class and smaller nobles being mostly on Luther's side, while the priests and reigning princes, with a few exceptions, were against him. In order to defend himself from misrepresentation and justify his course, he published two pamphlets, one called "An Appeal to the Emperor and Christian Nobles of Germany," and the other, "Concerning the Babylonian Captivity of the Church." These were read by tens of thousands, all over the country. Pope Leo X. immediately issued a bull, ordering all Luther's writings to be burned, excommunicating those who should believe in them, and summoning Luther to Rome. This only increased the popular excitement in Luther's favor, and on the 10th of December, 1520, he took the step which made impossible any reconciliation between himself and the Papal power. Accompanied by the Professors and students of the University, he had a fire kindled outside of one of the gates of Wittenberg, placed therein the books of canonical law and various writings in defence of the Pope, and then cast the Papal bull into the flames, with the words: "As thou hast tormented the Lord and His Saints, so may eternal flame torment and consume thee!" This was the boldest declaration of war ever hurled at such an overwhelming authority; but the courage of this one man soon communicated itself to the people. The knight, Ulric von Hutten, a distinguished scholar, who had been crowned as poet by the Emperor Maximilian, openly declared for Luther: the rebellious baron, Franz von Sickingen, offered him his castle as a safe place of refuge. Frederick the Wise was now his steadfast friend, and, although the dangers which beset him increased every day, his own faith in the righteousness of his cause only became firmer and purer. [Sidenote: 1519.]