Since the entirety of Holy Scripture is the word of the Lord, no testimony could possibly be better, more certain, or more efficacious. For if God, who cannot lie, has spoken something in his own Scripture, which is itself a mirror of his will, then it is true.On the Truth of Holy Scripture, 1.15
Scripture is the foundation of every Catholic opinion, and within it resides the very salvation of the faithful. Moreover, it is the exemplar and mirror designed to examine and extinguish every sort of error or heretical evil. Surely even a small error in this principle could bring about the death of the church.On the Truth of Holy Scripture, 1.1-2