Modern economic theory started with the Industrial Revolution of the 18th and 19th centuries. The steam engine was invented by John Watt in the same year that his friend, Adam Smith, published the Wealth of Nations. The transition from the notion of holding things for one’s own use and enjoyment to the notion of economic power over others evidently accompanies the historical evolution of property from slavery, feudalism, colonialism and a sparse population, to marketing, business and the pressure of population on limited resources. The concept of exclusive holding for use and enjoyment of self is identical with that aspect of property which we have distinguished as “economy.” To the medieval mind and the common law, property as such, the mere holding of lands and chattels, did not endow one with economic power. The Munn Case was an innovation in that it recognized a source of power unknown to the common law and unrevealed until property assumed its modern dimensions.