The "Liber Epistolarum sine Titulo" contains, as it is printed in his works (Basle edit., 1581), eighteen letters, fulminating as freely against papal luxury and corruption as if they had been penned by Luther or John Knox.

From their contents, we might set down Petrarch as the earliest preacher of the Reformation, if there were not, in the writings of Dante, some passages of the same stamp.

If these epistles were really circulated at the time when they were written, it is matter of astonishment that Petrarch never suffered from any other flames than those of love; for many honest reformers, who have been roasted alive, have uttered less anti-papal vituperation than our poet; nor, although Petrarch would have been startled at a revolution in the hierarchy, can it be doubted that his writings contributed to the Reformation.
It must be remembered, at the same time, that he wrote against the church government of Avignon, and not that of Rome.

He compares Avignon with the Assyrian Babylon, with Egypt under the mad tyranny of Cambyses; or rather, denies that the latter empires can be held as parallels of guilt to the western Babylon; nay, he tells us that neither Avernus nor Tartarus can be confronted with this infernal place.
"The successors of a troop of fishermen," he says, "have forgotten their origin.

They are not contented, like the first followers of Christ, who gained their livelihood by the Lake of Gennesareth, with modest habitations, but they must build themselves splendid palaces, and go about covered with gold and purple.