Everyone who observes himself doubting observes a truth, and about that which he observes he is certain; therefore he is certain about a truth. Everyone therefore who doubts whether truth exists has in himself a truth on which not to doubt.... Hence one who can doubt at all ought not to doubt the existence of truth.
The customs of God's people and the institutions of our ancestors are to be considered as laws. And those who throw contempt on the customs of the Church ought to be punished as those who disobey the law of God.
Whoever, therefore, thinks that he understands the divine scriptures or any part of them so that it does not build on the double love of God and of our neighbor does not understand it at all. Thus a man supported by faith, hope, and charity, with an unshaken hold upon them does not need the scriptures. . . And many live by these three things in solitude without books.
What difference, if you are mistaken? For if I am mistaken, I am. For he who is not, assuredly cannot be mistaken; and therefore I am, if I am mistaken. Therefore because I am if I am mistaken, how am I mistaken that I am, when it is sure that I am, if I am mistaken.
A Christian man is on his guard with respect to those who philosophize according to the elements of this world, not according to God, by Whom the world itself was made; for he is warned by the precept of the apostle and faithfully hears what has been said, 'Beware that no one deceive you through philosophy and vain deceit, according to the elements of the world'
Because a thing is eloquently expressed it should not be taken to be as necessarily true; nor because it is uttered with stammering lips should it be supposed false.
Don't hold yourselves cheap, seeing that the creator of all things and of you estimates your value so high, so dear, that he pours out for you every day the most precious blood of his only-begotten Son.
The most venerable, clearly understood, enlightened, and reliable constant in the world is not only that we want to be happy, but that we want only to be so. Our very nature requires it of us.