Pétau's leisure moments were given to deciphering old manuscripts and studying history. Every year saw some new book from his hands; meanwhile, his vast correspondence and his replies to his critics involved an immense amount of other labor. Though naturally of a mild disposition, his controversies unfortunately assumed the harsh and vituperative tone of the period. It was the accepted method. His great work on chronology appeared in 1627 and won universal applause; Philip IV of Spain offered him the chair of history in Madrid, but he refused it on the score of health. In 1637 he dedicated to Pope Urban VIII a "Paraphrase of the Psalms in Greek verse," for which he was invited to Rome, but he escaped the honor on the plea of age. As a matter of fact, he was so frightened at the prospect of being made a cardinal that he fell dangerously ill, and recovered only when assured that his name was removed from the list. He stopped teaching in 1644, only eight years before his death. The complete list of his books fills twenty-five columns in Sommervogel's catalogue of Jesuit publications. They are concerned with chronology, history, polemics, and the history of dogma. His "Dogmata theologica" is incomplete, not having been carried beyond the fifth volume. In those days there was an extraordinary amount of exaggerated confidence entertained by many of the dignitaries of the Church that the Jesuits had an especial aptitude for adjusting the politico-religious difficulties which were disturbing the peace of Europe. Thus, we find Father Warsewicz sent to Sweden in 1574 to strengthen the resolution of the king of that country, who, under the influence of his Catholic queen, was desirous of restoring the nation to the Faith. Warsewicz appeared in the court of King John, not as representing the Pope, but as the ambassador of the King of Poland, who was related to Queen Catherine. It was she who had suggested this means of approaching the king. Accordingly, private meetings were held with the monarch during an entire week, for five and six hours consecutively, for John prided himself on his theological erudition. He agreed to re-establish Catholicity in his realm, provided the chalice was granted to the laity and that marriage of the clergy and the substitution of Swedish for Latin in the liturgy were permitted. He had no difficulty about the doctrinal teaching of the Church.