In the relations between states, as in the relations of groups within a single state, what is to be desired is independence for each as regards internal affairs, and law rather than private force as regards external affairs. But as regards groups within a state, it is internal independence that must be emphasized, since that is what is lacking; subjection to law has been secured, on the whole, since the end of the Middle Ages. In the relations between states, on the contrary, it is law and a central government that are lacking, since independence exists for external as for internal affairs. The stage we have reached in the affairs of Europe corresponds to the stage reached in our internal affairs during the Wars of the Roses, when turbulent barons frustrated the attempt to make them keep the king's peace. Thus, although the goal is the same in the two cases, the steps to be taken in order to achieve it are quite different. There can be no good international system until the boundaries of states coincide as nearly as possible with the boundaries of nations. But it is not easy to say what we mean by a nation. Are the Irish a nation? Home Rulers say yes, Unionists say no. Are the Ulstermen a nation? Unionists say yes, Home Rulers say no. In all such cases it is a party question whether we are to call a group a nation or not. A German will tell you that the Russian Poles are a nation, but as for the Prussian Poles, they, of course, are part of Prussia. Professors can always be hired to prove, by arguments of race or language or history, that a group about which there is a dispute is, or is not, a nation, as may be desired by those whom the professors serve. If we are to avoid all these controversies, we must first of all endeavor to find some definition of a nation. A nation is not to be defined by affinities of language or a common historical origin, though these things often help to produce a nation. Switzerland is a nation, despite diversities of race, religion, and language. England and Scotland now form one nation, though they did not do so at the time of the Civil War. This is shown by Cromwell's saying, in the height of the conflict, that he would rather be subject to the domain of the royalists than to that of the Scotch. Great Britain was one state before it was one nation; on the other hand, Germany was one nation before it was one state. What constitutes a nation is a sentiment and an instinct, a sentiment of similarity and an instinct of belonging to the same group or herd. The instinct is an extension of the instinct which constitutes a flock of sheep, or any other group of gregarious animals. The sentiment which goes with this is like a milder and more extended form of family feeling. When we return to England after being on the Continent, we feel something friendly in the familiar ways, and it is easy to believe that Englishmen on the whole are virtuous, while many foreigners are full of designing wickedness.