IV. From the law of nature then which may also be called the law of nations, it is evident that all kinds of war are not to be condemned. In the same manner, all history and the laws of manners of every people sufficiently inform us, that war is not condemned by the voluntary law of nations. Indeed Hermogenianus has said, that wars were introduced by the law of nations, a passage which ought to be explained somewhat differently from the general interpretation given to it. The meaning of it is, that certain formalities, attending war, were introduced by the law of nations, which formalities were necessary to secure the peculiar privileges arising out of the law. From hence a distinction, which there will be occasion to use hereafter, between a war with the usual formalities of the law of nations, which is called just or perfect, and an informal war, which does not for that reason cease to be just, or agreeable to right. For some wars, when made upon just grounds, though not exactly conformable, yet are not repugnant to the law, as will be explained more fully hereafter. By the law of the nations, says Livy, provision is made to repel force by arms; and Florentinus declares, that the law of nations allows us to repel violence and injury, in order to protect our persons. V. A greater difficulty occurs respecting the divine voluntary law. Nor is there any force in the objection that as the law of nature is unchangeable, nothing can be appointed even by God himself contrary to it. For this is true only in those things, which the law of nature positively forbids or commands; not in those which are tacitly permitted by the same law. For acts of that kind, not falling strictly within the general rule, but being exceptions to the law of nature, may be either forbidden or commanded. The first objection usually made against the lawfulness of war is taken from the law given to Noah and his posterity, Gen. ix. 5, 6, where God thus speaks, "Surely the blood of your lives will I require; at the hand of every beast will I require it, and at the hand of every man; at the hand of every man's brother will I require the life of man. Whoever sheds man's blood, by man shall his blood be shed; for in the image of God made he man." Here some take the phrase of requiring blood, in the most general sense, and the other part, that blood shall be shed in its turn, they consider as a bare threat, and not an approbation; neither of which acceptations can be admitted. For the prohibition of shedding blood extends not beyond the law itself, which declares, THOU SHALT NOT KILL; but passes no condemnation upon capital punishments or wars undertaken by public authority.