In the year 1872 the Supreme Court of the United States was called upon, in the Slaughter House Cases, to interpret the meanings of the words Property and Liberty as used in the Constitution of the United States. The liberty of access to markets on the part of an owner is essential to the exchange-value of property, too much liberty of access on the part of would-be competitors is destructive of that exchange-value. The long-recognized goodwill of a business which had always possessed exchange-value, but which was merely the expected beneficial behavior of other people, became simply a special case of property. The common-law and popular notion of property as physical things is, therefore, but an elliptical statement of what common-sense can take for granted without the pedantry of explaining every time that what is meant by property is the uses and not the thing.