Coming from a family in poor circumstances, a Dominican friar from his fifteenth year, this great Pope as a simple Religious, as bishop, and as cardinal was famous for his intrepid defense of the Faith and discipline of the Church, and for the spotless purity of his life. The secret of his power lay in seeking the Glory of God alone, and in his constant attention to prayer. By this latter means he overcame the insolence of the Turks and sanctified the people entrusted to his care. His name adores the front page of the Roman Missal and Breviary, because it was by his authority that the revision to the liturgical books was brought to a conclusion. Since his time the Holy See and the entire hierarchy have followed definitely the road of that salutary revival of the ecclesiastical spirit which was marked out by the Council of Trent. He died in 1572. (Note: This was written before the errors of Vatican II).
(Source: The New Roman Missal by Father Lasance, p 1692)