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 country like Great Britain, there are considerable tracts of land which it is unprofitable to employ for any economic purpose whatsoever, and which possess no further value than what the mere pride of ownership may give them.  This fact makes it possible to apply the conception of the margin to the case of land with particularly illuminating results.

In the first place, however, it should be observed that the value of any piece of land does not depend solely on the intrinsic fertility of the soil.  The fact that land is an immobile thing makes its situation a factor of great importance.  In the case of urban land, situation is, of course, the only thing that counts.  The value of a site in Bond Street or the City is entirely unaffected by its capacity or incapacity for potato-growing purposes.  But even for agricultural land, situation is a most important matter.  A farm, which is so remote that considerable transport charges must be incurred to bring its produce to market, will be less sought after, and less valuable, than one which is much better situated though somewhat less fertile.  In what follows, therefore, we must speak of the “quality” of a piece of land in a broad sense to include advantages of situation, as well as of fertility.  Let us now, imagine the different pieces of land in Great Britain to be arranged in order of quality, so that we have a long series, with land of the best quality