IT is difficult to explain the national principle except in terms of crowd-hypnotism or, more kindly, as something for which people will die. Switzerland, with four languages, proves that common language is not essential. Nor are blood and common descent, geographical unity, common religion, common racial type, common institutions, military or literary traditions, or commercial interests. However, no national sentiment could well arise where some of them were not present.

Roughly speaking, national unity has usually preceded liberal institutions. In the early nineteenth century there was no question in Western countries like France and England of having to struggle for national unity, but the Western nations were the scene of violent efforts to liberalise the national institutions and sometimes to go further and win some kind of Socialist or Communist organisation. Ideas of this kind were less active farther East.