ankind is always struggling to
obtain food, and is able to multiply so rapidly as to exhaust any
conceivable increase of supplies. The landlord class alone profits.
The greater the struggle for supply the greater will be the share of
the whole produce which must be surrendered to it. Beyond this,
however, lies the further problem which specially occupied Ricardo.
How will the resulting strain affect the relations of the two
remaining classes, the labourers and the capitalists? The ultimate
evil of protection is the bad distribution of capital. But capital
always acts by employing labour. The farmer's capital does not act by
itself, but by enabling his men to work. Hence, to understand the
working of the industrial machinery, we have to settle the relation of
wages and profits. Ricardo states this emphatically in his preface.
Rent, profit, and wages, he says, represent the three parts into which
the whole produce of the earth is divided. 'To determine the laws
which regulate this distribution is the principal problem in political
economy'; and one, he adds, which has been left in obscurity by
previous writers.[300] His investigations are especially directed by
the purpose thus defined. He was the first writer who fairly brought
under distinct consideration what he held, with reason, to be the most
important branch of economical inquiry.

There was clearly a gap in the economic doctrine represented by the
_Wealth of Nations_. Adam Smith was primarily concerned with the
theory of the 'market.' He assumes the existence of the social
arrangement which is indicated by that phrase. The market implies a
constitution of industrial agencies such that, within it, only one
price is possible for a given commodity, or, rather, such that a
difference of price cannot be permanent. According to the accepted
illustration, the sea is not absolutely level, but it is always
tending to a level.[301] A permanent elevation at one point is
impossible. The agency by which this levelling or equilibrating
process is carried out is competition, involving what Smith called the
'higgling of the market.' The momentary fluctuation, again, supposes
the action of 'supply and demand,' which, as they vary, raise and
depress prices. To illustrate the working of this machinery, to show
how previous writers had been content to notice a particular change
without following out the collateral results, and had thus been led
into fallacies such as that of the 'me