e might
be willing to let his remuneration depend upon the result of the
enterprise, in which case the contract was one of _societas_. In
either case the right of the owner of the money to reap a profit from
the operation was unquestioned, provided only that he was willing to
share the risks of loss. But if, instead of making use of his money
for trading either by his own exertions or by those of his partner
or agent, he chose to sell his money, he was not permitted to receive
more for it than its just price--which was, in fact, the repayment of
the same amount. This was what happened in the case of a _mutuum_. In
that case the ownership of the money was transferred to the borrower,
who was perfectly at liberty to trade with it, if he so desired, and
to reap whatever gain that trade produced. The prohibition of usury,
far from being proof of the injustice of an income from capital, is
proof of quite the contrary, because it was designed to insure that
the income from capital should belong to the owner of that capital and
to no other person.[1] Although, therefore, no price could be paid for
a loan, the lender must be prevented from suffering any damage from
making the loan, and he might make good his loss by virtue of the
implied collateral contract of indemnity, which we discussed above
when treating of extrinsic titles. If the lender, through making the
loan, had been prevented from making a profit in trade, he might be
indemnified for that loss. All through the discussions on usury we
find express recognition of the justice of the owner of money deriving
an income from its employment; all that the teaching of usury was at
pains to define was who the person was to whom money, which was the
subject matter of a _mutuum_, belonged. It is quite impossible to
comprehend how modern writers can see in the usury teaching of the
scholastics a fatal discouragement to the enterprise of traders and
capitalists; and it is equally impossible to understand how
socialists can find in that doctrine any suggestion of support for the
proposition that all unearned income is immoral and unjust.

[Footnote 1: See Rambaud, _op. cit._, p. 59.]

SECTION 3.--THE MACHINERY OF EXCHANGE

We have already drawn attention to the fact that there was no branch
of economics about which such profound ignorance ruled in the earlier
Middle Ages as that of money. As we stated above, even as late as
the twelfth century, the theologians were quite c