One arrives best, perhaps, at the concept of political obligation by considering what is society and what is that particular form of society which is the political society. All men belong to societies, have some community with others—i.e. are compacted with them into a solidarity of one kind or another. Though this may arise in various ways, two main divisions are distinguishable, namely that coming from the division of labour and that coming from similitude. The former expresses our dependence on the planter of Brazil, the rancher of the Argentine, the fellah of Egypt. We all acknowledge our dependence on them, but would scarcely say that we formed a society with them. To admit this would be a manifest absurdity, but to deny it would be to deny the existence, or the possibility of the existence, of an international society of men. All that can be allowed is that there exists a certain inter-dependence which yet does not constitute a society.

But men are linked together by resemblances of which they may be ignorant, which are innate and which affect them physically and morally; resemblances coming from race, culture, language, customs, or an historical accident. The formation of ethnical and national groups provides a good example of this solidarity by similitude. Because these people are united by blood, because they are begotten by the same cultural and historical milieu, they are in harmony and have a common patriotic feeling. Yet even here it must be conceded that neither the ethnical group nor the nation is a society. The only way in which they can become this is by taking on themselves the political form of a State, a man-made construction.