He must have been fully occupied on the Last Judgment during 1536 and 1537. Paul III. was still in correspondence with the Duke of Urbino, who showed himself not only willing to meet the Pope's wishes with regard to the Tomb of Julius, but also very well disposed toward the sculptor. In July 1537, Hieronimo Staccoli wrote to the Duke of Camerino about a silver salt-cellar which Michelangelo had designed at his request. This prince, Guidobaldo della Rovere, when he afterwards succeeded to the Duchy of Urbino, sent a really warm-hearted despatch to his "dearest Messer Michelangelo." He begins by saying that, though he still cherishes the strongest wish to see the monument of his uncle completed, he does not like to interrupt the fresco in the Sistine Chapel, upon which his Holiness has set his heart. He thoroughly trusts in Michelangelo's loyalty, and is assured that his desire to finish the tomb, for the honour of his former patron's memory, is keen and sincere. Therefore, he hopes that when the picture of the Last Judgment is terminated, the work will be resumed and carried to a prosperous conclusion. In the meantime, let Buonarroti attend to his health, and not put everything again to peril by overstraining his energies. Signer Gotti quotes a Papal brief, issued on the 18th of September 1537, in which the history of the Tomb of Julius up to date is set forth, and Michelangelo's obligations toward the princes of Urbino are recited. It then proceeds to declare that Clement VII. ordered him to paint the great wall of the Sistine, and that Paul desires this work to be carried forward with all possible despatch. He therefore lets it be publicly known that Michelangelo has not failed to perform his engagements in the matter of the tomb through any fault or action of his own, but by the express command of his Holiness. Finally, he discharges him and his heirs from all liabilities, pecuniary or other, to which he may appear exposed by the unfulfilled contracts. III While thus engaged upon his fresco, Michelangelo received a letter, dated Venice, September 15, 1537, from that rogue of genius, Pietro Aretino. It opens in the strain of hyperbolical compliment and florid rhetoric which Aretino affected when he chose to flatter. The man, however, was an admirable stylist, the inventor of a new epistolary manner. Like a volcano, his mind blazed with wit, and buried sound sense beneath the scoriae and ashes it belched forth. Gifted with a natural feeling for rhetorical contrast, he knew the effect of some simple and impressive sentence, placed like a gem of value in the midst of gimcrack conceits. Thus: "I should not venture to address you, had not my name, accepted by the ears of every prince in Europe, outworn much of its native indignity. And it is but meet that that I should approach you with this reverence; for the world has many kings, and one only Michelangelo.