The term "group" serves as a convenient sociological designation for any number of people, larger or smaller, between whom such relations are discovered that they must be thought of together. The "group" is the most general and colorless term used in sociology for combinations of persons. A family, a mob, a picnic party, a trade union, a city precinct, a corporation, a state, a nation, the civilized or the uncivilized population of the world, may be treated as a group. Thus a "group" for sociology is a number of persons whose relations to each other are sufficiently impressive to demand attention. The term is merely a commonplace tool. It contains no mystery. It is only a handle with which to grasp the innumerable varieties of arrangements into which people are drawn by their variations of interest. The universal condition of association may be expressed in the same commonplace way: people always live in groups, and the same persons are likely to be members of many groups. Individuals nowhere live in utter isolation. There is no such thing as a social vacuum. The few Robinson Crusoes are not exceptions to the rule. If they are, they are like the Irishman's horse. The moment they begin to get adjusted to the exceptional condition, they die. Actual persons always live and move and have their being in groups. These groups are more or less complex, more or less continuous, more or less rigid in character. The destinies of human beings are always bound up with the fate of the groups of which they are members. While the individuals are the real existences, and the groups are only relationships of individuals, yet to all intents and purposes the groups which people form are just as distinct and efficient molders of the lives of individuals as though they were entities that had existence entirely independent of the individuals.