A significant concession concerning slavery, given by Nicholas in a brief issued to King Alfonso in 1454, extends the rights granted to existing territories to all those that might be taken in the future.
The new humanist learning had been regarded with suspicion in Rome as a possible source of schism and heresy from an unhealthy interest in paganism.
Nicholas V, reversing this trend, employs Lorenzo Valla to translate Greek histories, pagan as well as Christian, into Latin.
This industry, coming just before the dawn of printing, contributes enormously to the sudden expansion of the intellectual horizon.
Pope Nicholas V’s chief interest is his library, for which his agents, in pursuit of rare codices, scour Europe.
With assistance from Enoch of Ascoli and Giovanni Tortelli, Nicholas founds a library of nine thousand volumes.
The Pope himself is vastly erudite, and his friend Aeneas Silvius Piccolomini, later Pope Pius II, will later say of him that "what he does not know is outside the range of human knowledge" but will add that the luster of his pontificate would be forever dulled by the fall of Constantinople to the Ottoman Turks in 1453, a double blow to Christendom and to Greek letters.
"It is a second death," wrote Aeneas Silvius, "to Homer and Plato."
Nicholas V preaches a crusade and endeavors to reconcile the mutual animosities of the Italian states, but without much success.
He will not live long enough to see the effect of the Greek scholars who began to find their way to Italy armed with unimagined manuscripts.