79. In comparing the value of money with that of commodities,
we consider silver as a metal, which is an object of commerce. In
estimating the interest of money we attend to the use of it
during a determinate time.
In the market a measure of corn is purchased with a certain
weight of silver, or a quantity of silver is bought with a
certain commodity, it is this quantity which is valued and
compared with the value of other commodities. In a loan upon
interest, the object of the valuation is the use of a certain
quantity of property during a certain time. It is in this case no
longer a mass of silver, compared with a quantity of corn, but it
is a portion of effects compared with a certain portion of the
same, which is become the customary price of that mass for a
certain time. Let twenty thousand ounces of silver be an
equivalent in the market for twenty thousand measures of corn, or
only for ten thousand, the use of those twenty thousand ounces of
silver for a year is not worth less on a loan than the twentieth
part of the principal sum, or one thousand ounces of silver, if
interest is at five per cent.
