It is important that this be fully understood, for it shows that effects attributed by current theories to increase of population are really due to the progress of invention, and explains the otherwise perplexing fact that labor-saving machinery everywhere fails to benefit laborers.
Yet, to grasp fully this truth, it is necessary to keep in mind what I have already more than once adverted to—the interchangeability of wealth. I refer to this again, only because it is so persistently forgotten or ignored by writers who speak of agricultural production as though it were to be distinguished from production in general, and of food or subsistence as though it were not included in the term wealth.
Let me ask the reader to bear in mind, what has already been sufficiently illustrated, that the possession or production of any form of wealth is virtually the possession or production of any other form of wealth for which it will exchange—in order that he may clearly see that it is not merely improvements which effect a saving in labor directly applied to land that tend to increase rent, but all improvements that in any way save labor.
That the labor of any individual is applied exclusively to the production of one form of wealth is solely the result of the division of labor. The object of labor on the part of any individual is not the obtainment of wealth in one particular form, but the obtainment of wealth in all the forms that consort with his desires. And, hence, an improvement which effects a saving in the labor required to produce one of the things desired, is, in effect, an increase in the power of producing all the other things. If it take half a man's labor to keep him in food, and the other half to provide him clothing and shelter, an improvement which would increase his power of producing food would also increase his power of providing clothing and shelter. If his desires for
