The assertion is often made by railroad managers that railroad transportation is a private business as much as any other branch of commerce. It is not likely that these same managers would wish to have their argument carried to its logical conclusion, for, should the courts at any time take their view, they would be under the necessity of declaring null and void all their charters, which were granted to them upon the assumption that the railroad was a highway operated under the authority and control of the State by private companies for the public good. If, on the other hand, railroad managers are, for their own protection, forced to recognize the public character of railroads, they can no longer question the right of the State to so control their business as the public good may demand. And this shows the absurdity of the claim often made by railroad managers, that, as long as the rates charged by them are reasonable, the State has no right to interfere with their business, or, in other words, that they may discriminate between individuals and localities, and that they may legally practice a thousand other abuses as long as individual shippers find it beyond their power to prove that they have been charged exorbitant rates. Charles Fisk Beach, Jr., in his "Commentaries on the Law of Private Corporations," lays it down as a general principle of law that "whenever any person pursues a public calling and sustains such relations to the public that the people must of necessity deal with him, and are under a moral duress to submit to his terms if he is unrestrained by law, then, in order to prevent extortion and an abuse of his position, the price he may charge for his services may be regulated by law." And applying this principle to common carriers, and especially railroads, this author says: "The sovereign has always assumed peculiar control over common carriers as conducting a business in which the public has an interest, and in the case of railway carriers an additional basis of governmental control is grounded in the extraordinary franchise of eminent domain conferred upon these companies. For corporations engaged in carrying goods for hire as common carriers have no right to discriminate in freight rates in favor of one shipper, even when necessary to secure his custom, if the discriminating rate will tend to create a monopoly by excluding from their proper markets the products of the competitors of the favored shipper."