against the infidel,—thus, as Aeneas himself owned, seeking to cure one evil by another.
The chief interest perhaps of the efforts made by Nicholas and his successors to bring about an European peace, for the sake of driving back the Turk and recovering Constantinople, lies in the measure which they suggest of the distance which the world had travelled since the age of the Crusades. In the eleventh and in the twelfth, even in the thirteenth century, a religious sentiment could stir the princes and the peoples of Europe to go forth, not to avert a danger, but to rescue a holy place of pilgrimage. But in the fifteenth, though the unbeliever had won his way into Europe, had reached the Danube and threatened the Adriatic, the imminent danger to Christendom left Christendom lukewarm. Except religious zeal, there was no force which could compel an European effort. With the growth of "humanism" the old kind of religious enthusiasm had passed away. Pope Nicholas himself illustrated the change of things since the days of Urban II, when, at the very time of his proclaiming a Crusade, he privately sent agents to the East, to rescue from the deluge all Greek manuscripts they could lay hands on.
There were however special reasons, besides the general lukewarmness, that accounted for the failure of the first papal efforts. Nothing could be effectually done without the co-operation of Venice; and Venice, as we saw, made on her own account an advantageous treaty with Mohammad. The Emperor, who professed to support the idea of a Crusade, was hindered from energetic action by his ill relations with Hungary. The demand for money, which might have enabled the Pope to organise an armament, was highly unpopular. And not the least serious impediment was the intolerance which divided the Catholics from the Greek Church, and prevented them from feeling any true pity for the forlorn prospects of their fellow-Christians in Greece and Servia, or any sincere desire to save them. It was futile for Aeneas Sylvius to say that the Greeks were not heretics, but only schismatics; they were generally regarded as worse than infidels. The only prince who might have been ready to make sacrifices, if any common action had been organised, was Duke Philip of Burgundy. In the spring of 1454 a diet was held at Ratisbon, but the essential business was deferred to a second diet at Frankfort in the autumn; and it came to a third at Wienerisch-Neustadt (February, 1455). Aeneas Sylvius was persuasive and eloquent; but the meetings had no result. At the two later diets the appeals of John of Capistrano produced a sensation from which much was hoped. Like Peter the Hermit, he possessed the faculty of stirring the common folk in open-air assemblies. On the death of Pope Nicholas, the papal chair was filled by a Spaniard, Calixtus III (March, 1455), who seemed to have no less burning zeal for the holy war than John of Capistrano and Aeneas himself. He made a solemn vow to dedicate all his strength to the recovery of Constantinople and to the extermination of the "devilish