The original groups, the stems of the wild and barbarian people, were more strongly united than the animal groups. Family relationship and a common language strengthened this union further. Every individual had the support of the entire tribe. Under such conditions, the social motives, the moral feelings, the subordination of the individual to the whole, must have developed to the utmost. With the further development of society, the tribes are dissolved and their places are taken by new unions, by towns and peoples. New formations step into the place of the old ones, and the members of these groups carry on the struggle for existence in common against other peoples. In equal ratio with economic development, the size of these unions increases, the struggle of each against the other decreases, and social feelings spread. At the end of ancient times we find that all the people known then formed a unit, the Roman Empire, and at that time arose the theory――the moral feelings having their influence on almost all the people――which led to the maxim that all men are brothers. When we regard our own times, we see that economically all the people form one unit, although a very weak one; nevertheless the abstract feeling of brotherhood becomes ever more popular. The social feelings are strongest among members of the same class, for classes are the essential units embodying particular interests and including certain members. Thus we see that the social units and social feelings change in human society. These changes are brought about by economic changes, and the higher the stage of economic development, the higher and nobler the social feelings. VIII. TOOLS, THOUGHT AND LANGUAGE.