Moreover, the study of the theory of rent has had a very great influence on all branches of economics by destroying the notion that it is possible to draw sharp lines of distinction, or deal with economic conceptions as though they were entirely independent categories.
There are few if any conceptions in economics which cannot be expressed in it without depleting the ordinary vocabulary.
In times past, and to a less extent in our own day, philosophical conceptions have formed the basis of great systems of politics and economics.
It is in the adaptation of biological conceptions and methods, in the positive contributions of jurisprudence, law and history, in the rigorous application, where possible, of quantitative tests, that the explanation of the present position of economics is to be found.
And in the same spirit Mill desired, whilst incorporating all the results arrived at in the special science by Smith's successors, to exhibit purely economic phenomena in relation to the most advanced conceptions of his own time in the general philosophy of society, as Smith had done in reference to the philosophy of his century.