Its wisdom as a political measure cannot be doubted.

If the Emperor had had the sympathy of the Pope, and the championship of Catholic Europe, the Turks might not have entered Constantinople in 1453.

But they had not that sympathy, and the Turks did enter it; and no one event has ever left so lasting an impress upon civilization as the overthrow of the old Byzantine Empire, and the giving to the winds, to carry whither they would, its hoarded treasures of ancient ideals.

Byzantium had been the heir to Greece, and now Russia claimed to be heir to Byzantium; while the head of Russia was Moscow, and the head of Moscow was Ivan III., who had just settled himself firmly on the seat left by his father, "Vasili the Blind" (1462).
Christendom had never received such a blow.

Where had been before a rebellious and alienated brother, who might in time be reconciled, there was now--and at the very Gate of Europe--the infidel Turk, the bitterest and most dangerous foe to Christianity; bearing the same hated emblem that Charles Martel had driven back over the Pyrenees (in 732), and which had enslaved the Spanish Peninsula for seven hundred years; but, unlike the Saracen, bringing barbarism instead of enlightenment in its train.
The Pope, in despair and grief, turned toward Russia.