12 Then (again borrowing the words of Our Predecessor, Paul V), the Lord began to work His wonders in Charles. He filled him with a wisdom, justice, and burning zeal for promoting His glory and the Catholic cause. Above all, the Lord filled him with a great concern for restoring the faith in the Church universal according to the decrees of the renowned Council of Trent. That Pontiff himself, as well as all future generations, attributed the success of the Council to Charles, since even before carrying its decrees into action he was its most ardent promoter. In fact, his many vigils, trials, and labors brought its work to its ultimate completion.
Source: Editae Saepe (Vatican.va)