Petri, Olaus-Phase a Swedish theologian, was born at OErebro, in 1497: the son of a blacksmith, he received his early education among the Carmelites of his native town, together with his brother Laurent, with whom he attended the University of Wittenberg, where they embraced the doctrines of Luther. On their return to Sweden, in 1519, they began, after having as by a miracle escaped from the executioners of Christian II, to propagate the ideas of the Reformer. Appointed in 1523 rector of the school of Strengnas, Olauis won to his opinions the archdeacon Laurent Andrea, and, through the mediation of the latter, Gustavus Vasa appointed Peter preacher at Stockholm. In his sermons and in divers conferences he attacked the old religion with an increasing ardor. The first among all Protestant ecclesiastics in Sweden, he was publicly married in 1525. After having assisted at the Diet of Vesteras in 1527, where he had a dispute upon religion with the professor of Upsala, Pierre Galle, whom Gmlstavus declared to have been conquered, he entered more and more into the favor of the king, who consulted him upon the most important affairs, and finally appointed him his chancellor. In 1539 Petri, tired of business, exchanged his duties for those of first pastor of the capital. The following year he was condemned to death for not having revealed, in 1536, the conspiracy formed against the life of the king by some citizens of the Han'seatic villages, one of whom had confessed to him. He purchased his pardon for a large sum. Three years after the king reinstated him in his office of pastor, and he kept it until his death, which occurred at Stockholm in 1552. He joined to quite extensive and varied learning great activity and a captivating eloquence, but he never spared his adversary, and often degenerated into abuse of a bold and rash character. He may be called the Luther of Sweden, while his brother Laurent, milder and more moderate, was the Melancthon. We have of Petri's works, in Swedish, treatises on Marriage of Ecclesiastics (Stockholm, 1524, 1528, 4to): — the Difference between the Evangelical Faith and the Roman (ibid. 1527, 1605, 4to): — on the Duties of the Clergy and the Laity (ibid. 1528, 4to): — on the Inconveniences of the Monastic Life (ibid. 1528, 4to): — Postills on all the Evangelists (ibid. 1530): — Introduction to Sacred Scripture (ibid. 1538. 4to): — some Sermons, Odes that are still sung in Sweden, and several other theological writings. Petri has left in manuscript some Memoirs upon the history of his country, which remained unpublished because Gustavus found them written with too much independence; one copy of which, preserved in the Royal Library of Paris, has been analyzed by Keralio in the Notices et Extraits des Manuscrits, volume 1. — Hoefer, Nouv. Biog. Generale, 39:754. See also the references under the preceding article.