In order for a war to be just, three things are necessary. First, the authority of the sovereign. Secondly, a just cause. Thirdly, a rightful intention.

Sorrow can be alleviated by good sleep, a bath and a glass of wine.

A man has free choice to the extent that he is rational.

Good can exist without evil, whereas evil cannot exist without good.

Justice is a certain rectitude of mind whereby a man does what he ought to do in the circumstances confronting him.

The things that we love tell us what we are.

If forgers and malefactors are put to death by the secular power, there is much more reason for excommunicating and even putting to death one convicted of heresy.

Clearly the person who accepts the Church as an infallible guide will believe whatever the Church teaches.

Distinctions drawn by the mind are not necessarily equivalent to distinctions in reality.

The truth of our faith becomes a matter of ridicule among the infidels if any Catholic, not gifted with the necessary scientific learning, presents as dogma what scientific scrutiny shows to be false.

To bear with patience wrongs done to oneself is a mark of perfection, but to bear with patience wrongs done to someone else is a mark of imperfection and even of actual sin.

All the efforts of the human mind cannot exhaust the essence of a single fly.

Love is a binding force, by which another is joined to me and cherished by myself.

The test of the artist does not lie in the will with which he goes to work, but in the excellence of the work he produces.

There is nothing on this earth more to be prized than true friendship.

God should not be called an individual substance, since the principal of individuation is matter.

To live well is to work well, to show a good activity.

The theologian considers sin mainly as an offence against God; the moral philosopher as contrary to reasonableness.

Man cannot live without joy; therefore when he is deprived of true spiritual joys it is necessary that he become addicted to carnal pleasures.

The principal act of courage is to endure and withstand dangers doggedly rather than to attack them.

To one who has faith, no explanation is necessary. To one without faith, no explanation is possible.

Wonder is the desire for knowledge.

Temperance is simply a disposition of the mind which binds the passion.

If, then, you are looking for the way by which you should go, take Christ, because He Himself is the way.

Hold firmly that our faith is identical with that of the ancients. Deny this, and you dissolve the unity of the Church.

Because philosophy arises from awe, a philosopher is bound in his way to be a lover of myths and poetic fables. Poets and philosophers are alike in being big with wonder.

Perfection of moral virtue does not wholly take away the passions, but regulates them.

It is possible to demonstrate God's existence, although not a priori, yet a posteriori from some work of His more surely known to us.

Beware of the person of one book.

Moral science is better occupied when treating of friendship than of justice.

Every judgement of conscience, be it right or wrong, be it about things evil in themselves or morally indifferent, is obligatory, in such wise that he who acts against his conscience always sins.

The knowledge of God is the cause of things. For the knowledge of God is to all creatures what the knowledge of the artificer is to things made by his art.

Law; an ordinance of reason for the common good, made by him who has care of the community.

The highest manifestation of life consists in this: that a being governs its own actions. A thing which is always subject to the direction of another is somewhat of a dead thing.

Man should not consider his material possession his own, but as common to all, so as to share them without hesitation when others are in need.

We can't have full knowledge all at once. We must start by believing; then afterwards we may be led on to master the evidence for ourselves.

Better to illuminate than merely to shine, to deliver to others contemplated truths than merely to contemplate.

As regards the individual nature, woman is defective and misbegotten, for the active power of the male seed tends to the production of a perfect likeness in the masculine sex; while the production of a woman comes from defect in the active power.

Not everything that is more difficult is more meritorious.

How can we live in harmony? First we need to know we are all madly in love with the same God.

Three things are necessary for the salvation of man: to know what he ought to believe; to know what he ought to desire; and to know what he ought to do.

Law is nothing other than a certain ordinance of reason for the common good, promulgated by the person who has the care of the community.

Well-ordered self-love is right and natural.

In order for a war to be just, three things are necessary. First, the authority of the sovereign. Secondly, a just cause. Thirdly, a rightful intention.

Most men seem to live according to sense rather than reason.

Faith has to do with things that are not seen and hope with things that are not at hand.

Because we cannot know what God is, but only what He is not, we cannot consider how He is but only how He is not.

It is clear that he does not pray, who, far from uplifting himself to God, requires that God shall lower Himself to him, and who resorts to prayer not to stir the man in us to will what God wills, but only to persuade God to will what the man in us wills.

It is requisite for the relaxation of the mind that we make use, from time to time, of playful deeds and jokes.