After the term of his professorship had expired, about March 1, 1573, his special enemy, Bartolomé de Medina, was elected in his place and was promoted, in August 1576, to the leading chair in theology, while Fray García del Castillo succeeded to that of Durandus. On Fray Luis's return, he was warmly and honorably received in an assembly of the Senate, convoked for the purpose, where the Commissioner of the Inquisition declared that the Holy Office had ordered his restoration to honor and to his professorship. Luis however refused to disturb Castillo and, in January 1577, an extraordinary chair on the Scriptures was created for him. The next year, on the chair of moral philosophy falling vacant, he obtained it and subsequently he became regular professor of Scripture--one of the highest positions in the University. His colleague Grajal had been less fortunate, having perished in prison before the termination of his trial.[353] Fray Luis's mental vigor was unimpaired, although his delicate frame never wholly recovered from the effects of his long imprisonment. Such an experience of the dangers attendant on the discussions of the schools might seem sufficient to dampen his disputatious ardor, but in a theology, which sought to reduce to hard and fast lines all the secrets of the unknown spiritual world, there was risk of heresy in every speculation. In an _acto_ of the University, held January 20, 1582, the debate widened into a discussion upon predestination and free-will, in which Fray Luis and Fray Domingo de Guzman were bitterly opposed to each other. It was continued in another theological Act the next week; the students became excited and called upon Father Bañez to repress these novelties, which he did in a lecture declaring that the views of Fray Luis savored of Pelagianism. The latter was angered and the next day, in an assembly of all the faculties, the question under debate was: If God confers equal and sufficing grace on two men, nothing else interfering, can one be converted and the other reject the aid? The discussion between Fray Luis and Bañez was hot, and the excitement increased. Then on January 27th there was another assembly which wrangled over the intricate questions involved in prevenient aid and human coöperation.[354]