BY the law of nature, as here applicable, is understood certain principles and rights which exist anterior to all the laws and institutions of the social state, and cannot be abrogated by subsequent legislation. Such is the right of self-defense, for instance, which cannot be alienated. There are other natural rights which may be voluntarily relinquished; and there are still others which may be forfeited. Such is that of personal freedom, which may be lost by captivity in war, by crime, and by debt. Hence, though in the language of our Declaration of Independence, "all men are created equal," still they may forfeit that equality by either of the causes above specified. The right of war to take the persons of armed enemies, and so dispose of them as that their hostility shall become harmless, at least during the continuance of strife, or until they are exchanged, is practiced upon by all Christian nations; is established not only on the immutable basis of reason, but the natural right of self-defense. Among civilized nations possessing the means of securing their prisoners, and of maintaining them without inflicting personal labour, until they are exchanged for mutual convenience, a temporary loss of liberty only is the result of capture in war. But it is far otherwise with savage and barbarous nations, who have neither jails nor forts, nor dungeons nor prison-ships, in which to secure their prisoners; who have no superfluities wherewith to feed, and who are unacquainted with the humane expedient of exchanging them. When they capture more than they require for their own purposes, they must either let them go, sell them to others, or put them to death. Hence Aristotle maintains that slavery must and always will exist, so long as there are barbarous nations in the world.
It is an expedient of humanity and interest combined. It is based on the principle, that life is dearer than liberty to the great majority of mankind. It is a step in the progress of civilization, by substituting service, or sale, for the massacre of prisoners of war. Among the Indians of North America, the most savage race with which we are acquainted, prisoners were only made, for the purpose of supplying the places of those of their own tribe killed in battle, or to be tortured at the stake, for the gratification of the most malignant feelings of revenge. The early battles with them were massacres, and war extermination. When, in process of time, it became known to the savages that the French governors of Canada would purchase their white captives, they began to find it to their interest to preserve them; since, while they ridded themselves thus of their enemies, they at the same time converted them into sources of profit. Indiscriminate massacres, and tortures at the stake now became more rare, and were not resumed until a false spirit of philanthropy forbade the purchase of captives in war. A few instances also occur in our own history, of selling Indian prisoners to the planters of the West Indies, and the memory of our forefathers has been unjustly assailed on that account. But what could they do with them? They could not exchange them with their barbarous enemies; they were always deficient in the superfluities of life themselves; they had no means of securing their Indian captives, or of making them useful; and if they let them loose again, it was only to expose themselves anew to their depredations and murders.