saw walking off with one of his silver spoons. If, however, the thief threatens property of considerable value say, twenty pounds or so and the only way of saving the money is by taking the life of the thief, this would be lawful. Moreover, when a highwayman demands my purse or my life, I am not bound to hand him my purse, even though it contain little money; I may always defend myself from such unjust attacks, even though it finally involves the death of the aggressor.
3. It is not lawful to kill another who attacks my honour with insulting words. The contrary used to be held by some theologians, but the doctrine was condemned by Alexander VII and Innocent XI. The reason of the difference between this case and the foregoing is that verbal insults are often not of very serious consequence; they are better and more effectively met by quiet contempt than by being taken seriously, and that would be a perilous doctrine which taught that a man might avenge an insult with the death of the offender. What constitutes an insult is often a very subjective question, and the results of the doctrine would be deplorable.
4. What one may lawfully do, that, as a rule, another may help him to do; and so I may kill or maim an unjust assailant not only of my own life, limb, chastity, or property, but when any innocent person is similarly threatened I may also do the same in his defence. Although I may lawfully do this, yet there is seldom an obligation of doing it, for the obligation would only arise from charity, and as we saw above, this virtue does not usually bind with such serious inconvenience as would always be involved in taking life in defence of another. Those who have charge of the public peace and security are more strictly bound to perform their duty of protecting life and property even at the sacrifice of the lives of wrongdoers.
