If he employed unscrupulous means, he employed them against unscrupulous men--on the sound principle of similia similibus curantur--and to some extent they were justified by the ends in view.
He found the temporal throne of the Pontiffs tottering when he ascended it.

Stefano Porcaro and his distinguished following already in 1453 had attempted the overthrow of the pontifical authority, inspired, no doubt, by the attacks that had been levelled against it by the erudite and daring Lorenzo Valla.
This Valla was the distinguished translator of Homer, Herodotus, and Thucydides, who more than any one of his epoch advanced the movement of Greek and Latin learning, which, whilst it had the effect of arresting the development of Italian literature, enriched Europe by opening up to it the sources of ancient erudition, of philosophy, poetry, and literary taste.

Towards the year 1435 he drifted to the court of Alfonso of Aragon, whose secretary he ultimately became.

Some years later he attacked the Temporal Power and urged the secularization of the States of the Church.

"Ut Papa," he wrote, "tantum Vicarius Christi sit, et non etiam Coesari." In his De falso credita et ementita Constantini Donatione, he showed that the decretals of the Donation of Constantine, upon which rests the Pope's claim to the Pontifical States, was an impudent forgery, that Constantine had never had the power to give, nor had given, Rome to the Popes, and that they had no right to govern there.