WAGES, PROFITS AND INTEREST 173 
we shall consider shortly) gets as its pay is its 
marginal worth in production. 
This statement is sometimes expressed in 
another and more complicated form, which 
comes, however, to the same thing in sub 
stance. It is said, for instance with refer 
ence to labour, that wages must equal the 
discounted worth of the expectation of its 
marginal product. Strictly speaking the 
element of anticipation must be introduced, 
as it is here, because the work must be done 
before its result is attained, and wages are 
usually arranged prior to the performance of 
the work. And so also must the notion of 
discounting be introduced, in order to meet 
the case, which is a common one, in which the 
saleable product is not obtained until long after 
the labour has been paid for. Suppose that the 
addition of another labourer to a farmer’s staff, 
other things remaining unchanged, is expected 
to raise his harvest by 100 bushels of wheat 
a year, that the wheat is expected to be worth 
10s. a bushel and that the labourer works and 
is paid for fifty weeks in the year. Then the 
labourer would not get £1 a week (that is 
£50 a year, which is the expected value of his 
marginal product) because the product is not 
obtained until twelve months after his work 
begins ; but he would tend to get such an