The theory of monopoly is also of primary importance to the study of social development. The rise and fall and conflict of classes in defence of or in opposition to some form of monopoly may be significant factors in social change. The neglect of this will tend to lead to a colourless, unconvincing description of the process of development, and to a treatment of political, economic and moral factors in watertight compartments, each evolving by the aid of some a priori principle of progress of its own. Urban life, nevertheless, in its beginnings was in the main characterized by absence of monopoly and advantage. The relations at first within the gilds were for the most part those between independent producers. Considerations of class and national rivalries such as these that centre round institutional monopoly must not be disregarded as irrelevant in studying the effects of a system of enterprise and in estimating its contribution to social welfare.