208 
POLITICAL ECONOMY 
finished off. For its completion we require 
a finer instrument than has been employed 
hitherto ; we must lay aside the palette knife 
and take up the brush. The reader will 
guess that by the finer instrument the 
marginal method is meant. Without the use 
of this method a complete and consistent 
doctrine of rent is unattainable. It is true 
that we have already had recourse again and 
again in this chapter to the term “ marginal,” 
but the reader will not have failed to observe 
that in every case marginal quality has 
been intended. The conception of marginal 
quality does not incorporate the fundamental 
idea of what is known as the marginal 
method. 
It was posited at the outset of our de 
monstration that in farming every acre of 
land, whatever its quality and position with 
reference to the market, would have devoted 
to it the same amount of capital. Now this 
assumption, we all of us know, is a pure fiction. 
As a matter of fact the most fertile and the 
best situated land will be worked most inten 
sively, and by being worked most intensively 
we mean that most labour and capital 
will be applied to its cultivation per acre. 
We have, then, to determine how much labour 
and capital will be devoted to each plot of