The city is something more than a congeries of individual men and of social conveniences – streets, buildings, electric lights, tramways, and telephones, etc.; something more, also, than a mere constellation of institutions and administrative devices – courts, hospitals, schools, police, and civil functionaries of various sorts. The city is, rather, a state of mind, a body of customs and traditions, and of the organized attitudes and sentiments that inhere in these customs and are transmitted with this tradition. The city is not, in other words, merely a physical mechanism and an articifial construction. It is involved in the vital processes of the people who compose it; it is a product of nature, and particularly of human nature.