At Cologne Erasmus also met the man with whom, as a promising young humanist, fourteen years younger than himself, he had, for some months, shared a room in the house of Aldus's father-in-law, at Venice: Hieronymus Aleander, now sent to the Emperor as a papal nuncio, to persuade him to conform his imperial policy to that of the Pope, in the matter of the great ecclesiastical question, and give effect to the papal excommunication by the imperial ban.
It must have been somewhat painful for Erasmus that his friend had so far surpassed him in power and position, and was now called to bring by diplomatic means the solution which he himself would have liked to see achieved by ideal harmony, good will and toleration. He had never trusted Aleander, and was more than ever on his guard against him. As a humanist, in spite of brilliant gifts, Aleander was by far Erasmus's inferior, and had never, like him, risen from literature to serious theological studies; he had simply prospered in the service of Church magnates (whom Erasmus had given up early). This man was now invested with the highest mediating powers.
To what degree of exasperation Erasmus's most violent antagonists at Louvain had now been reduced is seen from the witty and slightly malicious account he gives Thomas More of his meeting with Egmondanus before the Rector of the university, who wanted to reconcile them. Still things did not look so black as Ulrich von Hutten thought, when he wrote to Erasmus: 'Do you think that you are still safe, now that Luther's books are burned? Fly, and save yourself for us!'
Ever more emphatic do Erasmus's protestations become that he has nothing to do with Luther. Long ago he had already requested him not to mention his name, and Luther promised it: 'Very well, then, I shall not again refer to you, neither will other good friends, since it troubles you'. Ever louder, too, are Erasmus's complaints about the raving of the monks at him, and his demands that the mendicant orders be deprived of the right to preach.
In April 1521 comes the moment in the world's history to which Christendom has been looking forward: Luther at the Diet of Worms, holding fast to his opinions, confronted by the highest authority in the Empire. So great is the rejoicing in Germany that for a moment it may seem that the Emperor's power is in danger rather than Luther and his adherents. 'If I had been present', writes Erasmus, 'I should have endeavoured that this tragedy would have been so tempered by moderate arguments that it could not afterwards break out again to the still greater detriment of the world.'
The imperial sentence was pronounced: within the Empire (as in the Burgundian Netherlands before that time) Luther's books were to be burned, his adherents arrested and their goods confiscated, and Luther was to be given up to the authorities. Erasmus hopes that now relief will follow. 'The Luther tragedy is at an end with us here; would it had never appeared on the stage.' In these days Albrecht Dürer, on hearing the false news of Luther's death, wrote in the diary of his journey that passionate exclamation: 'O Erasmus of Rotterdam, where will you be? Hear, you knight of Christ, ride forth beside the Lord Christ, protect the truth, obtain the martyr's crown. For you are but an old manikin. I have heard you say that you have allowed yourself two more years, in which you are still fit to do some work; spend them well, in behalf of the Gospel and the true Christian faith.... O Erasmus, be on this side, that God may be proud of you.'
It expresses confidence in Erasmus's power, but at bottom is the expectation that he will not do all this. Dürer had rightly understood Erasmus.
The struggle abated nowise, least of all at Louvain. Latomus, the most dignified and able of Louvain divines, had now become one of the most serious opponents of Luther and, in so doing, touched Erasmus, too, indirectly. To Nicholas of Egmond, the Carmelite, another of Erasmus's compatriots had been added as a violent antagonist, Vincent Dirks of Haarlem, a Dominican. Erasmus addresses himself to the faculty, to defend himself against the new attacks, and to explain why he has never written against Luther. He will read him, he will soon take up something to quiet the tumult. He succeeds in getting Aleander, who arrived at Louvain in June, to prohibit preaching against him. The Pope still hopes that Aleander will succeed in bringing back Erasmus, with whom he is again on friendly terms, to the right track.
But Erasmus began to consider the only exit which was now left to him: to leave Louvain and the Netherlands to regain his menaced independence. The occasion to depart had long ago presented itself: the third edition of his New Testament called him to Basle once more. It would not be a permanent departure, and he purposed to return to Louvain. On 28 October (his birthday) he left the town where he had spent four difficult years. His chambers in the College of the Lily were reserved for him and he left his books behind. On 15 November he reached Basle.
Soon the rumour spread that out of fear of Aleander he had saved himself by flight. But the idea, revived again in our days in spite of Erasmus's own painstaking denial, that Aleander should have cunningly and expressly driven him from the Netherlands, is inherently improbable. So far as the Church was concerned, Erasmus would at almost any point be more dangerous than at Louvain, in the headquarters of conservatism, under immediate control of the strict Burgundian government, where, it seemed, he could sooner or later be pressed into the service of the anti-Lutheran policy.