International relations have a long history, even if their character has changed from time to time to conform to changes in the concept of the nation and the structure of the state. The history of international law is, by contrast, extraordinarily brief. The period in which the existence of international law has had any influence on the character of international relations is briefer still; not until towards the end of the 18th century did this period begin. I shall argue that its commencement coincided with the final inauguration of the modern international system, and that one of the characteristics of the modern international system which distinguished it from all earlier systems of states is to be found in the fact that it was the first to pay regard to international law.