Without the favour of the pope he could not have held out for a moment against the enmity which his haughty and contemptuous ways roused against him. Therefore when Paul III died and Marcellus II succeeded him (April 9, 1555) Michelangelo was on the point of leaving Rome, but by the twenty-third of May Marcellus had died and Paul IV took his place. Michelangelo, again sure of the highest protection, went on with his fight. He would have thought himself dishonoured and would have feared for his salvation if he had given up the work.[{115}] "Against my will," he wrote in 1555, "I was entrusted with this task, and for eight years I have exhausted myself in vain in the midst of all kinds of trouble and weariness. Now that the construction is so far advanced that I can begin to vault the dome, to leave Rome would be to ruin the whole work, a great shame to me and for my soul a great sin."[90]
In 1557 Cosmo de' Medici begged him to come back to Florence "where honour and rest awaited him," but he answered firmly, "I can not leave here until I have carried the construction of St. Peter's so far that my plan can not be changed or destroyed and there will no longer be any possibility for thieves to begin their work again, as these scoundrels are only waiting for a chance to do. This is my resolve."
That same year his friends, who were afraid that he would carry his great designs with him into the grave, for none of them were written down, urged and besought until they succeeded in persuading him to execute a model in wood of the dome of St. Peter's.[91] He was still working on this in 1560.
The building went on, but not without many[{116}] difficulties. It was necessary in 1557 to rebuild almost the entire vault of the Chapel of the King of France because Michelangelo had been ill and unable to watch the work closely enough.
The attacks on him began again with fresh vigour at each mistake, and some of his best friends, like Cardinal Carpi, joined in them. Michelangelo heard from Francesco Bandini that the cardinal said everywhere that the work on St. Peter's could not be worse managed. Much hurt, he wrote to him at once that, "although he felt sure that the work was going on well, he feared that possibly his own enthusiasm and his age had blinded him and were, without his knowing it, a source of harm and danger to the building." In consequence he begged that they "would be so kind as to relieve him of the load which he had carried without pay for seventeen years under the orders of the popes." He offered his resignation. "A greater favour than its acceptance," he said, "could not be accorded him."[92]
His resignation was not accepted, and Pius IV in a pontifical letter gave him full powers and forbade that his plans should be set aside.
But Nanni di Baccio Bigio, indefatigable in his hate, moved heaven and earth to drive him away.[{117}] In 1562 Nanni appealed to Cosmo de' Medici for his aid in securing the appointment of architect of St. Peter's. Cosmo answered that he would do nothing about it while Michelangelo lived.
In 1563 the struggle became a tragic one. The head of the work at St. Peter's, Cesare de Casteldurante, was stabbed, and Pier Luigi Gaeta, Michelangelo's friend and one of his best aids, was thrown into prison on a false accusation of theft. Michelangelo responded to this by appointing Gaeta in Cesare's place. The committee of administration dismissed Gaeta and put Nanni in his place, and Michelangelo, beside himself with rage, no longer went to St. Peter's. His enemies did not lose this chance to spread the report that he was no longer willing to take charge of the building, and Michelangelo denied this in vain. The committee nominated a successor, and this successor was of course Nanni. Nanni cut loose at once from his master and began to give orders, for he thought that the old man of eighty-eight, weary at last of the struggle, would be forced either to submit or to resign. He did not know his antagonist. Michelangelo went at once to the pope and told him that if justice was not done he would leave Rome and go to Florence. The pope called the committee together and the members accused Michelangelo of having committed[{118}] errors which endangered the whole building. Michelangelo asked for an investigation and summoned Nanni to show the mistakes of which he accused him. Nanni could show nothing but his own bad faith, and was dismissed in disgrace.[93]
This did not prevent Nanni from sending, five months later, just after the death of Michelangelo, a letter by the Florentine ambassador to Cosmo de' Medici, asking again to be appointed his successor.
Until his last hour Michelangelo met with this fierce opposition over the work on St. Peter's, but his faith and his fighting spirit found in this only another reason for persevering.