But, while a change in the rate of wages in any particular occupation may induce a change in the relative demand for labor, it can produce no change in the aggregate demand. For instance, let us suppose that a combination of the workmen engaged in any particular manufacture raise wages in one country, while a combination of employers reduce wages in the same manufacture in another country. If the change be great enough, the demand, or part of the demand, in the first country will now be supplied by importation of such manufactures from the second. But, evidently, this increase in importations of a particular kind must necessitate either a corresponding decrease in importations of other kinds, or a corresponding increase in exportations. For, it is only with the produce of its labor and capital that one country can demand, or can obtain, in exchange, the produce of the labor and capital of another. The idea that the lowering of wages can increase, or the increase of wages can diminish, the trade of a country, is as baseless as the idea that the prosperity of a country can be increased by taxes on imports, or diminished by the removal of restrictions on trade. If all wages in any particular country were to be doubled, that country would continue to export and import the same things, and in the same proportions; for exchange is determined not by absolute, but by relative, cost of production. But, if wages in some branches of production were doubled, and in others not increased, or not increased so much, there would be a change in the proportion of the various things imported, but no change in the proportion between exports and imports. While most of the objections made to the combination of workmen for the advance of wages are thus baseless, while the success of such combinations cannot reduce other wages, or decrease the profits of capital, or injuriously affect national prosperity, yet so great are the difficulties in the way of the effective combinations of laborers, that the good that can be accomplished by them is extremely limited, while there are inherent disadvantages in the process.