than
he would if the products of the soil were equally distributed. Both
wages and profits must fall as more is left to rent, and that this
actually happens, he says, with unusual positiveness, is an
'incontrovertible truth.'[285] The fall enables the less fertile land
to be cultivated, and gives an excess of produce on the more fertile.
'This excess is rent.'[286] He proceeds to expound his doctrine by
comparing land to a set of machines for making corn.[287] If, in
manufacture, a new machine is introduced every one adopts it. In
agriculture the worst machines have still to be used; and those who
have the best and sell at the same price, can appropriate the surplus
advantage. This, he declares, is a law 'as invariable as the action of
the principle of gravity.'[288] Yet Smith and others have overlooked a
'principle of the highest importance'[289] and have failed to see that
the price of corn, as of other things, must conform to the cost of
production. The same doctrine was expounded in the same year by Sir
Edward West;[290] and, as it seems to me, more clearly and simply.
West, like Malthus, says that he has to announce a principle
overlooked by Adam Smith. This is briefly that 'each equal additional
quantity of work bestowed on agriculture yields an actually diminished
return.' He holds that profits fall as wealth increases, but he denies
Adam Smith's view that this is a simple result of increased
competition.[291] Competition would equalise, but would not lower
profits, for 'the productive powers of manufactures are constantly
increasing.' In agriculture the law is the opposite one of diminishing
returns. Hence the admitted fall of profits shows that the necessity
of taking inferior soils into cultivation is the true cause of the
fall.

Such coincidences as that between Malthus and West are common enough,
for very obvious reasons. In this case, I think, there is less room
for surprise than usual. The writer generally credited with the
discovery of the rent doctrine is James Anderson, who had stated it
as early as 1777.[292] The statement, however, did not attract
attention until at the time of West and Malthus it was forced upon
observers by the most conspicuous facts of the day. Adam Smith and
other economists had, as Malthus notices, observed what is obvious
enough, that rent in some way represented a 'net produce'--a something
which remained after paying the costs of production. So much was
obvious to any common