In these and other manifold ways the artificial conditions of city life have deprived the person of most of the natural outlets for the expression of his interests and his energies. To this fact is to be attributed in large part the restlessness, the thirst for novelty and excitement so characteristic of modern life. This emotional unrest has been capitalized by the newspapers, commercialized recreations, fashion, and agitation in their appeal to the sensations, the emotions, and the instincts loosened from the satisfying fixations of primary-group life. The _raison d'être_ of social work, as well as the fundamental problem of all social institutions in city life must be understood in its relation to this background. II. MATERIALS A. PHYSICAL CONTACT AND SOCIAL CONTACT 1. The Frontiers of Social Contact[121] Sociology deals especially with the phenomena of _contact_. The reactions which result from voluntary or involuntary contact of human beings with other human beings are the phenomena peculiarly "social," as distinguished from the phenomena that belong properly to biology and psychology. In the first place, we want to indicate, not the essence of the social, but the location, the sphere, the extent, of the social. If we can agree where it is, we may then proceed to discover what it is. The social, then, is the term next beyond the individual. Assuming, for the sake of analysis, that our optical illusion, "the individual," is an isolated and self-sufficient fact, there are many sorts of scientific problems that do not need to go beyond this fact to satisfy their particular terms. Whether the individual can ever be abstracted from his conditions and remain himself is not a question that we need here discuss. At all events, the individual known to our experience is not isolated. He is connected in various ways with one or more individuals. The different ways in which individuals are connected with each other are indicated by the inclusive term "contact." Starting, then, from the individual, to measure him in all his dimensions and to represent him in all his phases, we find that each person is what he is by virtue of the existence of other persons, and by virtue of an alternating current of influence between each person and all the other persons previously or at the same time in existence. The last native of Central Africa around whom we throw the dragnet of civilization, and whom we inoculate with a desire for whiskey, adds an increment to the demand for our distillery products, and affects the internal revenue of the United States, and so the life-conditions of every member of our population. This is what we mean by "contact." So long as that African tribe is unknown to the outside world, and the world to it, so far as the European world is concerned, the tribe might as well not exist. The moment the tribe comes within touch of the rest of the world, the aggregate of the world's