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.

• 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.
• The principal act of courage is to endure and withstand dangers doggedly rather than to attack them.
• 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.
• To one who has faith, no explanation is necessary. To one without faith, no explanation is possible.
• Faith has to do with things that are not seen and hope with things that are not at hand.
• 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.
• Hold firmly that our faith is identical with that of the ancients. Deny this, and you dissolve the unity of the Church.
• There is nothing on this earth more to be prized than true friendship.
• Friendship is the source of the greatest pleasures, and without friends even the most agreeable pursuits become tedious.
• Moral science is better occupied when treating of friendship than of justice.