[35] Buckle (Chap. II., History of Civilization) recognizes the necessary relation between rent, interest, and wages, but evidently never worked it out. CHAPTER III. OF INTEREST AND THE CAUSE OF INTEREST. Having made sure of the law of rent, we have obtained as its necessary corollary the law of wages, where the division is between rent and wages; and the law of wages and interest taken together, where the division is between the three factors. What proportion of the produce is taken as rent must determine what proportion is left for wages, if but land and labor are concerned; or to be divided between wages and interest, if capital joins in the production. But without reference to this deduction, let us seek each of these laws separately and independently. If, when obtained in this way, we find that they correlate, our conclusions will have the highest certainty. And, inasmuch as the discovery of the law of wages is the ultimate purpose of our inquiry, let us take up first the subject of interest. I have already referred to the difference in meaning between the terms profits and interest. It may be worth while, further, to say that interest, as an abstract term in the distribution of wealth, differs in meaning from the word as commonly used, in this: That it includes all returns for the use of capital, and not merely those that pass from borrower to lender; and that it excludes compensation for risk, which forms so great a part of what is commonly called interest. Compensation for risk is evidently only an equalization of return between different employments of capital. What we want to find is, what fixes the general rate of interest proper? The different rates of compensation for risk added to this will give the current rates of commercial interest. Now, it is evident that the greatest differences in what is ordinarily called interest are due to differences in risk; but it is also evident that between different countries and different times there are also considerable variations in the rate of interest proper. In California at one time two per cent. a month would not have been considered extravagant interest on security on which loans could now be effected at seven or eight per cent. per annum, and though some part of the difference may be due to an increased sense of general stability, the greater part is evidently due to some other general cause. In the United States generally the rate of interest has been higher than in England; and in the newer States of the Union higher than in the older States; and the tendency of interest to sink as society progresses is well marked and has long been noticed. What is the law which will bind all these variations together and exhibit their cause?