The fundamental principle of human action—the law that is to political economy what the law of gravitation is to physics—is that men seek to gratify their desires with the least exertion. Evidently, this principle must bring to an equality, through the competition it induces, the reward gained by equal exertions under similar circumstances. When men work for themselves, this equalization will be largely affected by the equation of prices; and between those who work for themselves and those who work for others, the same tendency to equalization will operate. Now, under this principle, what, in conditions of freedom, will be the terms at which one man can hire others to work for him? Evidently, they will be fixed by what the men could make if laboring for themselves. The principle which will prevent him from having to give anything above this, except what is necessary to induce the change, will also prevent them from taking less. Did they demand more, the competition of others would prevent them from getting employment. Did he offer less, none would accept the terms, as they could obtain greater results by working for themselves. Thus, although the employer wishes to pay as little as possible, and the employee to receive as much as possible, wages will be fixed by the value or produce of such labor to the laborers themselves. If wages are temporarily carried either above or below this line, a tendency to carry them back at once arises. But the result, or the earnings of labor, as is readily seen in those primary and fundamental occupations in which labor first engages, and which, even in the most highly developed condition of society, still form the base of production, does not depend merely upon the intensity or quality of the labor itself. Wealth is the product of two factors, land and labor, and what a given amount of labor will yield will vary with the powers of the natural opportunities to which it is applied. This being the case, the principle that men seek to gratify their desires with the least exertion will fix wages at the produce of such labor at the point of highest natural productiveness open to it. Now, by virtue of the same principle, the highest point of natural productiveness open to labor under existing conditions will be the lowest point at which production continues, for men, impelled by a supreme law of the human mind to seek the satisfaction of their desires with the least exertion, will not expend labor at a lower point of productiveness while a higher is open to them. Thus the wages which an employer must pay will be measured by the lowest point of natural productiveness to which production extends, and wages will rise or fall as this point rises or falls.