The life of man in society provides the subject-matter for many different sciences. It is analysed usually by reference to the kind of relation which connects men; and so, if men buy or sell one from the other, economics gives an account of the factors in such a relation; if a policeman directs traffic and the citizen obeys, political science explains government. But clearly no one of these relations between men is altogether independent of the others. Social life is the whole complex of human relations, and there is no man at all who is not thoroughly social. The fundamental fact of mental life life is not the atomic but the related individual. No mind exists which is not in contact with other minds; and there is no mind whose fundamental characteristics are not social.