BAIUS or DE BAY, MICHAEL (1513-1589), Belgian theologian, was born at Melun in Hainault. Educated at Louvain, he studied philosophy and theology and held various chairs there; in 1552 Charles V. made him professor of scriptural interpre tation. At Louvain he was a leader in the anti-scholastic reaction under the banner of St. Augustine and so came into conflict with Rome on the vexed questions of grace and free-will. In 1567 Pius V. condemned 79 of his propositions in the Bull Ex omnibus af flictionibus. Baius submitted, but indiscreet utterances by himself and his supporters led to a new condemnation in 1579 by Gregory XIII. Baius, however, kept his professorship, and became chanXiii. Baius, however, kept his professorship, and became chan- cellor of Louvain in 1575; he died there on Sept. i S, 1589. Baius is interesting as a forerunner of Cornelius Jansen (see JANSEN). His writings are described by Harnack as a fusion of Catholic orthodoxy with elements of Protestantism which were not re garded as such by Baius himself. The chief note of his teaching was the importance of sin, original and actual.
His principal works were published in a collected form at Cologne (1696) ; some large treatises have not been published. See F. X. von Linsenmann, Michael Baius, and die Grundlegung des Jansenismus (Tubingen, 1867) .