The life of states is like that of men. Men have a right to kill in the case of natural defense ; states have a right to wage war for their own preservation.
In the case of natural defense, I have a right to kill because my life is mine, as the life of my attacker is his ; in the same way, a state wages war because its preservation is just as is every other preservation.
Among citizens, the right of natural defense does not carry with it the necessity of attack. Instead of attacking, they have only to petition the courts. Therefore they can exercise the right of this defense only in momentary cases where it would be fatal to await rescue by the laws. But among societies the right of natural defense sometimes carries with it the necessity of attack, when one people sees that a longer peace would put another in a position to destroy it, and that attacking is at that moment the only way to prevent that destruction.
Whence it follows that small societies more often have the right to wage war than large ones, because they are more often in the position of fearing they will be destroyed.
The right of war therefore derives from necessity and strict justice. If those who direct the conscience or the counsels of princes do not limit themselves to that, all is lost ; and when they base themselves on arbitrary principles of glory, advantage, or utility, rivers of blood will inundate the earth.
Above all, let not the prince’s glory be invoked : his glory would be his pride ; it is a passion and not a legitimate right.
It is true that the reputation of his might could increase the forces of his state ; but the reputation of his justice would increase them just as much.