tch the whole social stock of instruments
of production, we shall see the no-rent points not fixed in location,
but shifting from place to place. Now this machine, now another, and
now still another reaches the unproductive state and is supplanted by
instruments of similar kind that are new and efficient.

_Original Elements in the Soil._--The real difference between the rent
of a piece of land and that of a building, machine, vehicle, or any
similar instrument arises from the fact that the land is not going to
destruction and the artificial instrument is. There are elements in
what is commonly called land that wear out as do the tools that are
used in tilling it, but these elements are not land in the economic
sense. Land, as Ricardo long ago said, consists in the "original and
indestructible powers of the soil." He singles out certain constituent
elements of every farm, forest, building site, or other piece of what
is called land in ordinary usage, and gives to this new concept the
name _land_ in an economic sense. These so-called "powers" are
original elements because man does not make them; they are provided
altogether by nature, and the only way in which man may be said to
impart any productive power to them is by putting them into
combinations in which they can produce. When men settle upon what has
been vacant land, they bring the land into combination with labor, and
when they break up the land for tillage and put buildings on it, they
combine it with artificial capital. By means of these combinations
land acquires productive power; but physically considered, it is
altogether a natural product.

_Indestructible Elements in the Soil._--Land in the economic sense is
indestructible because the natural effect of use is not to destroy it.
This does not mean that it is not physically possible to destroy land
to the extent of making it forever impracticable to use it in the ways
in which land is commonly utilized. Nature may do this by sinking it
beneath the ocean, and man can, if he will, do something akin to this;
but he does not naturally destroy what is truly land in the using. It
is impossible to use a plow, a spade, or a reaping machine without
injuring it and, in the end, wearing it out. It is also impossible to
draw the nutritive constituents out of the superficial loam and
convert them into crops without exhausting the supply of these sources
of fertility and so spoiling that which is commonly called the land