1. _Monopoly gets its power from political, economic, and commercial sources._ A political monopoly derives its power of control from a special grant from the government, forbidding others to engage in that business. The typical political monopoly is that conferred by a crown patent bestowing the exclusive right to carry on a certain business. A second kind is that conferred by a patent for invention, or the copyright on books, the object of which is to stimulate invention, research, and writing by giving the full control and protection of the government to the inventor and writer or their assignees. In this case the privilege is socially earned by the monopolist; it is not gotten for nothing. Moreover, the patent is limited in time, expires and becomes a social possession. A third kind is a government monopoly for purposes of revenue. In France, the government controls the tobacco trade, and the high price charged for tobacco makes the monopoly yield a large income. A fourth kind are public franchises for public service, as street-railways, lights, gas, waterworks, etc. These are granted to private capitalists to induce them to invest capital in something which has public utility. [Sidenote: Economic monopoly] Economic monopoly arises when the ownership of scarce natural agents, as mines, land, water-power, comes under the control of one man or one group of men who agree on a price. Economic monopoly is a result of private property that is undesigned by the government or by society. It is exceptional, considering the whole range of private property, but it is important. The oil-wells embracing the main sources of the world's supply have come under one control. One corporation may control so many of the richest iron-mines of the country as to be able to fix a price different from that which would result under competition. Coal-mines, especially those of some peculiar and limited kind, such as anthracite, appear to become easily an object of monopolization. Economic monopoly merges into political monopolies, such as patents and franchises. Private property is a political institution designed to further social welfare, and only rarely is any particular property a monopoly. Private control of great natural resources doubtless would have been prohibited had it been foreseen. [Sidenote: Commercial monopoly] Commercial monopoly, variously called contractual, organized, or capitalistic monopoly, arises where men unite their wealth to control a market, to overpower or intimidate opposition, and to keep out or limit competition by the mere magnitude of their wealth. These various kinds so merge into each other that they cannot always be distinguished in practice. A patent may help a capitalistic monopoly in getting control of a market; great wealth may enable a company to get control of rare natural resources. [Sidenote: Special classes of monopoly]