for the sake of more perfect understanding of the conditions applicable to each. Chapter XXI. Principles Of Interest. _Reasons for interest._—The propriety of interest under any circumstances has often been questioned, and its rightfulness is still bitterly disputed. Both church and state have at times denounced the receiving of interest as criminal. Yet in actual practice of commercial life throughout the world interest has been sustained in all ages. The Jewish law prohibited interest between neighbors, where the reason for borrowing was assumed to be poverty, but authorized it in dealings with foreigners, where the transaction was assumed to be in trade. The principle upon which interest in all productive industry is actually founded is that capital, gained by exertion and saved by self-control, secures to its present possessor such advantages of time and choice of use for his abilities as can be given by nothing else. In the study of production we have seen that time-saving is an important result of capital in its various forms. A carpenter’s kit of tools represents a value in use equal at least to the time he might consume in making them. He can afford to keep them for another’s use only while they bring to him the advantage of that time-saving. His neighbor is willing to secure him in that advantage by paying him for the use of the tools all, or nearly all, that he gains by using tools over what he would have without them. The borrower will still be the gainer by opportunity to do work not possible without the tools. The bargain between borrower and lender, like any bargain, is a fair one only when both are benefited. The limits of fairness in the deal are naturally reached when a clear understanding of all conditions is had in open market. Neither borrower nor lender can take advantage of the other without fraud. Neither is under obligation to give to the other without an equivalent. The whole question rests upon service rendered, as truly as in any other bargain.