Thomas Aquinas

The sin against nature is the most grievous of sins.

The greater the good that is contemned, the greater the sin. But the good of the species is greater than the good of the individual. Therefore, the sin against nature, which is against the good of the species, is greater than the sin of fornication, which is against the good of the individual.

It is worse to commit the sin of sodomy than to commit the sin of bestiality.

The act of generation is more noble than the act of nutrition.

It is not lawful for a man to have sex with his wife if she is unwilling.

But it is lawful for a husband to demand the marriage debt from his wife, even if she is unwilling, because she owes it to him by virtue of the marriage contract.

It is lawful to deceive the enemy in a just war.

It is lawful to kill a man who is an enemy of the commonwealth, even if he is not actually committing a crime.

It is lawful to take usury from Jews.

It is lawful to compel infidels to the faith, if they are subject to the Church, but not those who are outside the Church.

The Jews are not to be compelled to the faith, but they are to be allowed to live among Christians, provided they do not blaspheme Christ or the saints.

It is lawful to appropriate the goods of infidels, if they are warring against the Church.

The custom of the Church is to refuse baptism to the children of Jews and other infidels, because they are not yet capable of having faith.

It is lawful for a man to have more than one wife, if it be for the sake of begetting children.

The custom of the Church, which is guided by the Holy Ghost, is to be observed in all things.

It is lawful to kill a thief who is resisting arrest.

The death penalty is not contrary to the natural law, because it is for the common good.

It is lawful for a judge to condemn a man to death, if he is a murderer.

The killing of a man is not always a sin, but sometimes it is a duty.

It is lawful to swear by God, provided it be for a just cause.