groups which I have described. The members of the unit group work together. The Australian or Bushman hunter goes abroad to seek meat food, while the woman stays by the fire at a trysting place, with the children, and collects plant food. They cooperate in the struggle for existence, and the size of the group is fixed by the number who can work together to the greatest advantage under their mode of life. Such a group, therefore, has a common interest. It must have control of a certain area of land; hence it comes into collision of interest with every other group. The competition of life, therefore, arises between groups, not between individuals, and we see that the members of the in-group are allies and joint-partners in one interest while they are brought into antagonism of interest with all outsiders. It is the competition of life, therefore, which makes war, and that is why war always has existed and always will. It is in the conditions of human existence. In the cases which have been cited of nature peoples who have no war, we have heard mention already of division of hunting grounds and of quarrels which arise about them. Wherever there is no war, there we find that there is no crowding, as among the scattered Eskimo, or that, after long fighting, treaties and agreements have been made to cover all relations of interest between the groups. These we call peace-pacts, and it is evident that they consist in conventional agreements creating some combination between the groups which are parties to the agreement.
Each group must regard every other as a possible enemy on account of the antagonism of interests, and so it views every other group with suspicion and distrust, although actual hostilities occur only on specific occasion. Every member of another group is a stranger; he may be admitted as a guest, in which case rights and security
