The history of civilization is, in great measure, the history of the progressive appropriation by mankind of the various resources of the natural world. To know what men do and what they have is to know practically all that history can tell us about what they are.

Even Aristotle, in spite of his contempt for all forms of mechanical industry, was obliged, when endeavouring to reduce the elements of the State to their simplest form, to include the ideas of property and acquisition. He defines a possession as an instrument for maintaining life; and the history of ownership is, in fact, a history of the way in which people live, or of the things wherewithal they sustain their lives. What a man takes, what he enjoys, what he uses; what he appropriates or identifies with himself by custom, thought, and affection,—this more than anything else goes to build up the fabric of his everyday existence. But, as the objects which come to be regarded as property increase in number, the social and political significance of their possession increases also; and we have to learn, not only what commodities are regarded as wealth in each community, but also how they are obtained or produced, under what conditions and for what considerations they circulate or change hands, and what conditions law and custom impose on their final possession, enjoyment, or use.