A definition of a franchise has been given by the Supreme Court in terms of sufficient general accuracy to be adopted: "A franchise is a right, privilege, or power of public concern which ought not to be exercised by private individuals at their mere will and pleasure, but which should be reserved for public control and administration, either by the Government directly or by public agents acting under such conditions and regulations as the Government may impose in the public interest and for the public security."[14] A necessary condition, then, is a public interest in the occupation or privileges to be followed. The good will of a person or individual trader is not a franchise in this sense, though a franchise may be enjoyed by an individual as well as by a corporation, and good will may rest upon the privilege implied in the franchise. [Footnote 14: California vs. Southern Pacific Railroad, 127 U. S., 40.] The recognition of franchises, a species of property "as invisible and intangible as the soul in a man's body," as a proper object for taxation is now beyond any dispute. It is peculiarly appropriate as a source of revenue for the exclusive use of the State, inasmuch as the grant of franchises emanates from the State in its sovereign capacity. In the case of Morgan _vs._ the State of Louisiana, Justice Field, of the Supreme Court of the United States, said: "The franchises of a railroad corporation are rights or privileges which are essential to the operation of the corporation and without which its roads and works would be of little value, such as the franchise to run cars, to take tolls, to appropriate earth and gravel for the bed of its road, or water for its engines, and the like. They are positive rights or privileges, without the possession of which the road or company could not be successfully worked. Immunity from taxation is not one of them."[15] Further, the extent to which this taxation of franchises may be carried rests entirely in the discretion of the taxing power, subject only to constitutional restrictions. [Footnote 15: 93 U. S. Reports, pp. 217, 224.]