The most interesting adventure under the rule of Mercurian is the attempt to penetrate Sweden. The principles of the Reformation had been cordially received in Sweden, and it seemed to King John III. that peace could be secured only by some kind of compromise between the old faith and the new. John was, however, married to the sister of the Queen of Poland, and the Jesuits, who were sternly forbidden to enter the kingdom, saw in this a means of outwitting the vigilant Protestants. The combination of women and Jesuits was the supreme agency in checking the progress of the Reformation in Europe.
In 1574 an envoy came to Stockholm to convey the compliments of Anne of Poland to her sister Catherine. One could not close the gates against an envoy, though it was known that the fine clothes of the ambassador were a thin disguise of the Polish Jesuit Father Warsevicz, and the secret instructions of the envoy were to correct the liberalism of John and offer him an alliance with Spain. John knew theology and wrangled with the envoy for a week in the palace. The mission was fruitless, and in 1576 John was persuaded to countenance an even more romantic adventure. A young Norwegian presented himself to the Protestant clergy of Stockholm, and said that, having spent some years at southern universities, he would like a place as professor in the new college they were forming. He begged that they would recommend him to the king, and they did, so that he secured the appointment. It was the Jesuit Father Nicolai, who had, as John knew, been sent from Rome with instructions to perpetrate this amazing fraud. Nicolai must certainly have lied to the Protestant authorities about his beliefs, in order to obtain a place as teacher of theology in a Protestant college. When we reflect that he acted on instructions from Rome, and that no Jesuit or pro-Jesuit writer seems to see anything reprehensible in his conduct, we feel that Jesuit diplomacy had already reached a stage which it would be impolite to characterise in plain English.
Nicolai seems to have held his chair of Lutheran theology for a considerable time. There were those who scented heresy in his lectures, but they were promptly expelled, and Nicolai even became rector of the college. One would give much to have to-day a copy of the Lutheran-Jesuit's lectures. The masterful Possevin was next dispatched, in the quality of Legate, with the Irish Jesuit, William Good, for companion. He was to prevent a union of Sweden and Holland, and to correct the king's errors. Possevin went first to Prague, where he induced the widow of Maximilian to name him her ambassador to Sweden, and then, dressed for the part, with a sword dangling at his side, he boldly entered Stockholm, where Professor Nicolai was still teaching Lutheran theology in his subtle way. The counter-Reformation had different methods from those of Luther. John was willing to return to the faith and enter the Spanish alliance, if Rome would grant the marriage of priests, the mass in Swedish, and other claims of the Reformers. Possevin hastened to Rome, leaving his sword by the way, and stormily pressed the commission of cardinals to grant these concessions. It is (apart from certain remarkable indulgences later on the foreign missions) the only occasion on which a Jesuit pleaded for compromise, but Possevin was ambitious. Failing to obtain the concessions, Possevin hurried to the Duke of Bavaria, the Emperor, and the King of Poland, in order that he might at least be able to offer to John the material alliances he had promised him, if he would break with England and Holland. But he had little to offer, and the Protestants were now alarmed; and Possevin, Good, Warsevicz, and Professor Nicolai were politely ushered from the country.