In the spring of 1317 John condemned them, and, when they still preached revolt, summoned about sixty of them to Avignon. They used very plain speech and received a very plain reply. The Papacy had now discovered that persistent or "contumacious" disobedience amounted to heresy, and the Inquisitors belonged to the rival Dominican order. So several sons of St. Francis were burned at the stake--four were burned at Marseilles on May 7, 1318--and many were cast into prison. But John went too far. He ordered the Franciscan authorities to consider whether absolute poverty was the genuine basis of their rule, and they decided that it was: in the sense of a Bull (_Exiit qui seminat_) of Nicholas III., which allowed them "the use" of things without the actual "ownership." John revoked the Bull, and in a Decretal of December 8, 1322 (_Ad Conditorem_), declared that this was impossible nonsense. When the friars retorted that such poverty had actually been practised by Christ and his Apostles, John consulted the learned doctors of Paris and, in the Decretal _Cum inter nonnullos_ (November 12, 1323), pronounced this thesis heretical. The "Spirituals" were now reinforced by abler men, who fled to Italy and joined the anti-Papal campaign of Louis of Bavaria. Michael de Cesena, the General of the Order, nailed to the door of Pisa cathedral a document in which he impeached John for heresy. William of Ockham, the English friar, one of the most acute of the later schoolmen, and others, discharged a shower of invectives which would have made the fortune of a sixteenth-century Reformer. John was "Anti-Christ," the "Dragon with Seven Heads," and so on. They induced Louis of Bavaria to declare John's Decretals heretical, and fought shoulder to shoulder with the learned Paris doctors, Marsiglio of Padua and Jean of Jandun, whose _Defensor Pacis_ (1324) was a crushing indictment of the Papal pretensions and vindication of the secular power. All over Italy and Germany there was a fierce scrutiny of the bases of the Papal claims. The Reformation was commencing, two centuries before Luther. The spiritual struggle had thus merged in the political struggle, owing to the common opposition to John XXII., and this must now be considered. Frederic of Austria and Louis of Bavaria were both chosen King of the Romans, and, as neither had had the full number of votes, there was the not unfamiliar struggle for recognition. They disregarded John's summons to his tribunal, took to the sword, and Frederic was beaten and imprisoned in 1322. John coldly acknowledged Louis's letter announcing his victory; unquestionably he from the first wanted the imperial crown to pass to France and the imperial rule to vanish from Italy. Then Louis invaded Italy, and John declared war.