_The General Law of the Extension of the Margin of Cultivation._--Sometimes, when labor moves to new land that is now at the margin, it takes its new equipment with it; but such land is not always tilled by independent settlers. Employing farmers may set men working on it and pay them all that they produce; and the farmers may furnish the men with capital of their own or borrow capital for them to use. In either case a static condition requires the equalizing of the productivity of labor at the intensive margin with that of labor at the extensive margin; and it requires a similar leveling of the productivity of capital at the two margins. When this leveling has taken place in both cases, the all-around marginal product of labor fixes the rate of wages, and that of capital fixes the rate of interest. What a man creates on the good land and with the adequate capital, or on poor land with proportionate capital,--in any occupation on land of either grade,--determines the pay that he and other men can get. It constitutes in itself the wages of labor. In so far as the overflow of labor and capital into any one limited region of marginal land is concerned, the full statement is this: that the margin of utilization of land will be extended to the point at which a unit of labor, _using as much of the marginal land as it is economical to use, and such amount of auxiliary capital as is economical to combine with this unit of labor and the land it occupies, will create a product equal to the wages of the unit of labor as they are determined by the product it created when it was employed on the good land and in connection with the full equipment of auxiliary capital_.