It is not worth while to dwell more than has hitherto incidentally been done upon the failure of the current political economy to determine the true law of interest. Its speculations upon this subject have not the definiteness and coherency which have enabled the accepted doctrine of wages to withstand the evidence of fact, and do not require the same elaborate review. That they run counter to the facts is evident. That interest does not depend on the productiveness of labor and capital is proved by the general fact that where labor and capital are most productive interest is lowest. That it does not depend reversely upon wages (or the cost of labor), lowering as wages rise, and increasing as wages fall, is proved by the general fact that interest is high when and where wages are high, and low when and where wages are low. Let us begin at the beginning. The nature and functions of capital have already been sufficiently shown, but even at the risk of something like a digression, let us endeavor to ascertain the cause of interest before considering its law. For in addition to aiding our inquiry by giving us a firmer and clearer grasp of the subject now in hand, it may lead to conclusions whose practical importance will be hereafter apparent. What is the reason and justification of interest? Why should the borrower pay back to the lender more than he received? These questions are worth answering, not merely from their speculative, but from their practical importance. The feeling that interest is the robbery of industry is widespread and growing, and on both sides of the Atlantic shows itself more and more in popular literature and in popular movements. The expounders of the current political economy say that there is no conflict between labor and capital, and oppose as injurious to labor, as well as to capital, all schemes for restricting the reward which capital obtains; yet in the same works the doctrine is laid down that wages and interest bear to each other an inverse relation, and that interest will be low or high as wages are high or low.[36] Clearly, then, if this doctrine is correct, the only objection that from the standpoint of the laborer can be logically made to any scheme for the reduction of interest is that it will not work, which is manifestly very weak ground while ideas of the omnipotence of legislatures are yet so widespread; and though such an objection may lead to the abandonment of any one particular scheme, it will not prevent the search for another.