Quotes from St. Thomas Aquinas

Again, it is self-evident that truth exists. For truth exists if anything at all is true, and if anyone denies that truth exists, he concedes that it is true that it does not exist, since if truth does not exist it is then true that it does not exist.

If, then, the final happiness of man does not consist in those exterior advantages which are called goods of fortune, nor in goods of the body, nor in goods of the soul in its sentient part, nor in the virtues of practical intellect, called art and prudence, it remains that the final happiness of man consists in the contemplation of truth.

The person who truly understands love could love anyone.

Whatever is received into something is received according to the condition of the receiver

If our opponent believes nothing of divine revelation, there is no longer any means of proving the articles of faith by reasoning, but only of answering his objections--if he has any--against faith. Since faith rests upon infallible truth, and since the contrary of a truth can never be demonstrated, it is clear that the arguments brought against faith cannot be demonstrations, but are difficulties that can be answered.

Reason in man is rather like God in the world.

The Philosopher, too, says of the wicked (Ethic. ix, 4) that "their soul is divided against itself . . . one part pulls this way, another that"; and afterwards he concludes, saying: "If wickedness makes a man so miserable, he should strain every nerve to avoid vice.

nothing can be known, save what is true;

Temperance is simply a disposition of the mind which sets bounds to the passions

Honor is due to God and to persons of great excellence as a sign of attestation of excellence already existing; not that honor makes them excellent.

Beware of the person of one book.

Hence it is written (Wis. 9:14): "The thoughts of mortal men are fearful, and our counsels uncertain." Thus man needs to be guarded by the angels. Reply