The purposes of organized society in New York City, as in every metropolitan community, are made manifest through groups. By no means exclusively political, these purposes are social, cultural, and economic; they are expressed as objectives of individuals identified with each other by having common national and racial origins, common religion or residence or partisan affiliation. The articulation of these purposes is accomplished through group representatives who, in one way or another, acquire power over their fellows. Relationships between individuals composing these groups are of two kinds: vertical and horizontal. In each vertical group, there is a hierarchy of power, with the few at the top of the pyramid exercising authority over those below—authority that is never unlimited, but always dependent on the observance of established modes of behavior and the recognition of sudden shifts of opinion. The horizontal relationships between the officials on comparable levels of the various vertical groups are normally cooperative in character; but in certain cases they are combative. The theory of the party system requires, for example, the leaders of the parties to contend with each other for the support of the marginal voters. All of the individuals composing these groups are humanly frail and uncertain in their loyalties. Consequently, the equilibrium of forces just described is often disturbed by revolt within the vertical associations and by the constant re-formation of alliances among the horizontal groups.