"Believing that changes in International Law have been ultimately an expression of changes in the state system of the world and in the practice of the nations, we have tried, as it were, to cut into the procession of history at fixed points, to select some central theme at each stage, and to treat it in the light of history and law. In this attempt we arrived at a division of history from our point of view into three major periods which we have termed respectively those of the Prince, of the Judge, and of the Concert. In the first period, the scholar is still in the age of the dissolving Holy Roman Empire; in the second, commercial and dynastic wars - above all, the long-drawn-out struggle between France and England - dominate the scene; in the third and last, it is the voice of some force other than that of pure nationalism which, whatever the reason, reasserts itself. No division of this kind can be wholly satisfactory, but it is our belief that under one or another of these headings almost every issue which has interest for the historian of the Law of Nations can be conveniently treated." -- from the Preface by the author.