that there are certain things the use of
which consists in their consumption: thus we consume wine when we use
it for drink and we consume wheat when we use it for food. Wherefore
in such like things the use of the thing must not be reckoned apart
from the thing itself, and whoever is granted the use of the thing,
is granted the thing itself and for this reason, to lend things of
this kind is to transfer the ownership. Accordingly if a man wanted
to sell wine separately from the use of the wine, he would be selling
the same thing twice, or he would be selling what does not exist,
wherefore he would evidently commit a sin of injustice. In like
manner he commits an injustice who lends wine or wheat, and asks for
double payment, viz. one, the return of the thing in equal measure,
the other, the price of the use, which is called usury.

On the other hand, there are things the use of which does not consist
in their consumption: thus to use a house is to dwell in it, not to
destroy it. Wherefore in such things both may be granted: for
instance, one man may hand over to another the ownership of his house
while reserving to himself the use of it for a time, or vice versa,
he may grant the use of the house, while retaining the ownership. For
this reason a man may lawfully make a charge for the use of his
house, and, besides this, revendicate the house from the person to
whom he has granted its use, as happens in renting and letting a
house.

Now money, according to the Philosopher (Ethic. v, 5; Polit. i, 3)
was invented chiefly for the purpose of exchange: and consequently
the proper and principal use of money is its consumption or
alienation whereby it is sunk in exchange. Hence it is by its very
nature unlawful to take payment for the use of money lent, which
payment is known as usury: and just as a man is bound to restore
other ill-gotten goods, so is he bound to restore the money which he
has taken in usury.

Reply Obj. 1: In this passage usury must be taken figuratively for
the increase of spiritual goods which God exacts from us, for He
wishes us ever to advance in the goods which we receive from Him: and
this is for our own profit not for His.

Reply Obj. 2: The Jews were forbidden to take usury from their
brethren, i.e. from other Jews. By this we are given to understand
that to take usury from any man is evil simply, because we ought to
treat every man as our neighbor and brother, especially in the state
of the Go