ere is another bearing of this point of equal significance.
Political economists have a dismal formula called the Law of
Diminishing Returns, which casts a dark shadow upon industrial
progress as it is commonly conceived. The more food and clothing,
fuel, and other material goods we require, the further we have to go
for the material, and the harder it is to get: we must plough inferior
lands yielding smaller crops, we must sink deeper shafts for our coal
and iron. As our population grows ever larger, and this larger number
wants more and more pieces of the earth to feed its machines and to
turn out the increased quantity of goods, the drain upon natural
resources is constantly increasing. The material world is limited; in
time Nature will become exhausted, and, long before this happens, the
quantity of human labour required to raise the increased supply of raw
material in the teeth of the Law of Diminishing Returns will far
exceed the economies attending large-scale machine-production.

This danger will also be found to result entirely from the
quantitative estimate of human wealth and human life.

Confining our view for the moment to that branch of production which
is engaged in providing food, to which the Law of Diminishing Returns
is held to apply with special rigour, we can see without difficulty
how, by a progressive differentiation of consumption, we can mitigate
or even utterly defeat the operation of this law. If the inhabitants
of a country persist in maintaining a single narrow standard of diet,
and use the whole of their land for growing wheat and raising sheep,
not merely do they waste all other fine productive qualities belonging
to certain portions of the cultivated or uncultivated soil, but every
increase in their narrow consumption drives them to worse soil,
obliges them to put more labour into a quarter of wheat or a sheep,
and increases the proportion of their aggregate product which goes as
rent.[292] If, on the other hand, a community cultivates a varied
consumption and seeks to utilise each portion of its soil for whatever
form of food it can grow best, instead of grading its land exclusively
according to its wheat or sheep-raising capacity, it is able to defeat
the "niggardliness of nature" which asserts itself when the community
insists upon a continual extension of the same demands. For land which
may be very bad for wheat-growing or grazing, which may even be "below
the margin of cultivation"