In this lecture, after controverting the doctrine of an eminent French writer, who contended that there was no such thing as international law, and that the word law is not applicable to the obligations incumbent upon nations, on the ground that law is a rule of conduct prescribed by a superior; and that nations, being independent, acknowledge no superior, and have no common sovereign from whom they can receive law,--Mr. Adams proceeds to maintain that "by the law of nations is to be understood, not one code of laws, binding alike on all the nations of the earth, but a system of rules varying according to the character and condition of the parties concerned." There is a law of nations, among Christian communities, which is the law recognized by the constitution of the United States as obligatory upon them in their intercourse with European states and colonies. But we have a different law of nations regulating our intercourse with the Indian tribes on this continent; another, between us and the woolly-headed natives of Africa; another, with the Barbary powers; another, with the flowery land, or Celestial empire. This last is the nation with which Great Britain is now at war. Then, reasoning on the rights of property, established by labor, by occupancy, and by compact, he maintains that the right of exchange, barter,--in other words, of commerce,--necessarily follows; that a state of nature among men is a state of peace; the pursuit of happiness man's natural right; that it is the duty of men to contribute as much as is in their power to one another's happiness, and that there is no other way by which they can so well contribute to the comfort and well-being of one another as by commerce, or the mutual exchange of equivalents. These views and principles he thus illustrates: "The duty of commercial intercourse between nations is laid down in terms sufficiently positive by Vattel, but he afterwards qualifies it by a restriction, which, unless itself restricted, annuls it altogether. He says that, although the general duty of commercial intercourse is incumbent upon nations, yet every nation may exclude any particular branch or article of trade which it may deem injurious to its own interest. This cannot be denied. But, then, a nation may multiply these particular exclusions, until they become general, and equivalent to a total interdict of commerce; and this, time out of mind, has been the inflexible policy of the Chinese empire. So says Vattel, without affixing any note of censure upon it. Yet it is manifestly incompatible with the position which he had previously laid down, that commercial intercourse between nations is a moral obligation incumbent upon them all.