He busied himself in this retreat by finishing a work begun three years before, which he had better have left wholly undone. It was founded on a curious incident, of which he has preserved the knowledge, and which otherwise would have sunk into oblivion. There were a set of young men at Venice, disciples of Aristotle, or rather of his Arabian translator, Averroes, who set up his philosophy as the law of the world, who despised the Christian religion, and turned the apostles and fathers of the church into ridicule: there was an open war of opinion between these men and the pious Petrarch. Four among them, in the presumption and vivacity of youth, instituted a kind of mock tribunal, at which they tried the merits of their amiable and learned countryman; and pronounced the sentence, that "Petrarch was a good sort of a man, but exceedingly ignorant." He relates this incident in his treatise, "On my own Ignorance and that of others," which he commences by pretending to be satisfied with the decision. "Be it so," he says, "I am content; let my judges be wise, while I am virtuous!" and then he goes on to prove the fallacy of their judgment by a great display of erudition. [Sidenote: May 7. 1371. Ætat. 67.] He continued to get weaker, and his illnesses were violent, though transient. On one occasion he was attacked by a fever, and the physician sent to him by Francesco da Carrara, declared that he could not survive the night. The next morning he was found, apparently well, risen from his bed and occupied by his books. "This," he says, "has happened to me ten times in the course of ten years." The vital powers were thus exhausted, and it was not likely that he could live to extreme age. [Sidenote: Padua, Jan. 5. 1372. Ætat. 68.]