The Political Economy of the century following the publication of the "Wealth of Nations" dealt more with static problems than with dynamic ones. It sought to obtain laws which fixed the "natural" prices of goods and those which, in a like way, governed the natural wages of labor and the interest on capital. This term _natural_ as thus used, was equivalent to static. If the laws of value, wages, and interest had at this time been correctly stated, they would have furnished standards to which, in the absence of all change and disturbance, actual values, wages, and interest would ultimately have conformed. The economic theory of this time succeeded in formulating, correctly or otherwise, principles of economic statics and a fragment or two of a science of economic dynamics, although the distinction between the two divisions of the science was not clearly before the writers' eyes. The law of population contained in the work of Malthus is the only systematic statement then made of a general law of economic change. Though histories of wages, prices, etc., furnished some material for a science of Economic Dynamics, none of them attained the dignity of a presentation of law or merited a place in Economic Theory. Students of Political Economy were at that date scarcely awakened to the perception of laws of dynamics, and still less were they conscious of the need of a systematic statement of them. A modest beginning in the way of formulating such laws the present work endeavors to make.