The lending of money without interest, was very common, before the introduction of trade and industry. Money then was considered as a barren stock, incapable of producing fruit; and whenever the quantity of it, in any country, exceeded the uses of circulation, the remainder was locked up in treasures. In that light, the exacting of interest for it appeared unreasonable. Things are now changed: no money is ever locked up; and the regular payment of interest for it, when borrowed, is as essential to the obtaining of credit, as the confidence of being repaid the capital. These periodical payments are a constant corroboration of this confidence; so that it may be said, with truth, that he who can give good security, to pay to perpetuity, a regular interest for money, will obtain credit for any sum, although it should appear evident, that he never can be in a capacity to refund the capital. The reason of this may be gathered from the principles already deduced, and from the plan of our modern oeconomy. We have said in the second book, that the current money of a country is always in proportion to the trade, industry, consumption, and alienation, which regularly takes place in it; and when it happens that the money already in the country is not sufficient for carrying on these purposes, a part of the solid property, equal to the deficiency, may be melted down (as we have called it) and made to circulate in paper. That so soon again as this paper augments beyond that proportion, a part of what was before in circulation, must return upon the debtor in the paper, and be realized anew. Now let us consider what is understood by _realized_. By this term is meant, that the regorging paper, or that quantity of currency which a nation possesses over and above what is necessary for its circulation, must be turned into some shape whereby it may produce an income; for it is now a maxim, that no money is to be suffered to remain useless to the proprietor of it. When this _regorging_ paper then comes upon the debtor in it, if he should pay the value of it in hard specie, how would the condition of the creditor be improved?