ollow that the price and
rent of land will tend constantly to increase. John Stuart Mill,
accordingly, in the middle of the last century, asserted that "the
ordinary progress of a society, which increases in wealth, is at all
times tending to augment the incomes of landlords; to give them both a
greater amount and a greater proportion of the wealth of the
community, independently of any trouble or outlay, incurred by
themselves,"[1] and upon the strength of this assertion, he justified
the policy of imposing a special tax upon what we have come to call
the "unearned increment" of land. But how far does actual experience
bear his assertion out? In Great Britain we have seen in the last
half-century an undoubted increase in urban rents; but over long
periods at least, there was a marked fall in both the prices and rents
of agricultural land, despite the fact that the country was
"increasing in wealth" as rapidly as ever before. This was due, of
course, in the main to the increased supplies of wheat and other
foodstuffs coming from the New World: and if, accordingly, we choose
to lump together not only our own urban and agricultural land, but the
land of other countries as well, and to speak vaguely of the demand
for land as a whole, it might seem as though we could argue that
Mill's generalization still holds good. But even this is by no means
certain and in any case such a generalization is of very little
service: what the illustration should rather suggest to us, is the
danger of speaking of land vaguely as a whole, and the importance of
turning our attention to the variations in value between different
kinds and different pieces.

[Footnote 1: _Principles of Political Economy_, by John Stuart Mill.]

Sec.3. _The Differential Aspect_. Most ordinary commodities are not
produced on a single, uniform pattern. As a rule there are many
variations of grade and quality, and consequently of price. But these
variations are usually designed to meet the differences of taste among
the purchasers, and we do not expect to find that any variety of an
ordinary commodity will be produced, which is so poor in quality as to
be entirely valueless. But since it is nature which has produced the
land, without any assistance or guidance from man, there are many
pieces of land which are so unfertile, or are otherwise so unsuitable
for productive purposes, as to be quite valueless from the economic
standpoint. Even in a densely populated cou