All the theological discussion on the subject, and all the authoritative ecclesiastical declarations indicate, therefore, that interest on loans is to-day regarded as lawful because a loan is the economic equivalent of an investment. Evidently this is good logic and common sense. If it is right for the stockholder of a railway to receive dividends, it is equally right for the bondholder to receive interest. If it is right for a merchant to take from the gross returns of his business a sum sufficient to cover interest on his capital, it is equally right for the man from whom he has borrowed money for the enterprise to exact interest. The money in a loan is economically equivalent to, convertible into, concrete capital. It deserves, therefore, the same treatment and the same rewards. The fact that the investor undergoes a greater risk than the lender, and the fact that the former often performs labour in connection with the operation of his capital, have no bearing on the moral problem; for the investor is repaid for his extra risk and labour by the profits which he receives, and which the lender does not receive. As a mere recipient of interest, the investor undergoes no more risk nor exertion than does the lender. His claim to interest is no better than that of the latter. _Interest on Productive Capital_ On what ground does the Church or Catholic theological opinion justify interest on invested capital? on the shares of the stockholders in corporations? on the capital of the merchant and the manufacturer? In the early Middle Ages the only recognised titles to gain from the ownership of property were labour and risk.[137] Down to the beginning of the fifteenth century substantially all the incomes of all classes could be explained and justified by one or other of these two titles; for the amount of capital in existence was inconsiderable, and the number of large personal incomes insignificant. When, however, the traffic in rent charges and the operation of partnerships, especially the "contractus trinus," or triple contract, had become fairly common, it was obvious that the profits from these practices could not be correctly attributed to either labour or risk. The person who bought, not the land itself, but the right to receive a portion of the rent thereof, and the person who became the silent member of a partnership, evidently performed no labour beyond that involved in making the contract. And their profits clearly exceeded a fair compensation for their risks, inasmuch as the profits produced a steady income. How then were they to be justified?