Grotius draws the distinction between the law of nature and the law of nations thus: "When several persons at different times and in various places maintain the same thing as certain, such coincidence of sentiment must be attributed to some general cause. Now, in the questions before us, that cause must necessarily be one or the other of these two—either a just consequence drawn from natural principles, or a universal consent; the former discovers to us the law of nature, and the latter the law of nations."
Vattel defines the "necessary law of nations" to be the "application of the law of nature to nations." He says: "It is 'necessary,' because nations are absolutely bound to observe it. This law contains the precepts prescribed by the law of nature to States, on whom that law is not less obligatory than on individuals; since States are composed of men, their resolutions are taken by men, and the law of nations is binding on all men, under whatever relation they act. This is the law which Grotius, and those who follow him, call the Internal Law of Nations, on account of its being obligatory on nations in the point of conscience."
Vattel says again: "Nations being composed of men naturally free and independent, and who before the establishment of civil societies lived together in the state of nature, nations or sovereign States are to be considered as so many free persons living together in the state of nature."
And again: "Since men are naturally equal, and a perfect equality prevails in their right and obligations as equally proceeding from nature, nations composed of men, and considered as so many free persons living together in the state of nature, are naturally equal, and inherit from nature the same obligations and rights. Power or weakness does not in this respect produce any difference. A dwarf is as much a man as a giant; a small republic no less a sovereign State than the most powerful kingdom."
In these two last sentences is touched the key-note of the true law of nations, as well as of the true law for individuals—justice. There is among some of the later writers on jurisprudence a certain fashion of condescending speech in their quotations from Vattel. As years have gone on, and States have grown more powerful, and their relations more complicated by reason of selfishness and riches, less and less has been said about the law of nature as a component and unalterable part of the law of nations. Fine subtleties of definition, of limitation have been attempted. Hundreds of pages are full of apparently learned discriminations between the parts of that law which are based on the law of nature and the parts which are based on the consent and usage of nations. But the two cannot be separated. No amount of legality of phrase can do away with the inalienable truth underlying it. Wheaton and President Woolsey to-day say, in effect, the same thing which Grotius said in 1615, and Vattel in 1758.
Says Wheaton: "International law, as understood among civilized nations, may be defined as consisting of those rules of conduct which reason deduces as consonant to justice from the nature of the society existing among independent nations."
President Woolsey says: "International law, in a wide and abstract sense, would embrace those rules of intercourse between nations which are deduced from their rights and moral claims; or, in other words, it is the expression of the jural and moral relations of States to one another.
"If international law were not made up of rules for which reasons could be given satisfactory to man's intellectual and moral nature, if it were not built on principles of right, it would be even less of a science than is the code which governs the actions of polite society."
It is evident, therefore, that the one fundamental right, of which the "law of nations" is at once the expression and the guardian, is the right of every nation to just treatment from other nations, the right of even the smallest republic equally with "the most powerful kingdom." Just as the one fundamental right, of which civil law is the expression and guardian, is the right of each individual to just treatment from every other individual: a right indefeasible, inalienable, in nowise lessened by weakness or strengthened by power—as majestic in the person of "the dwarf" as in that of "the giant."
Of justice, Vattel says: "Justice is the basis of all society, the sure bond of all commerce. ***