_Labor as a Permanent Entity._--The term _labor_ is sometimes used to describe a permanent aggregation of laborers no one of whom lives and works through more than a brief period. Labor is thus analogous to capital and laborers to capital goods. A permanent working force is composed of perishable beings as a permanent producing fund is composed of perishable goods. Both are commonly described by the use of abstract terms, but both are in reality concrete things; and actually to reduce either to a mere abstraction would be to put a material entity out of existence. We instinctively speak of a value--a given number of dollars--in describing a man's capital, but it is dollars "invested in" productive instruments; and we instinctively speak of labor when we mean an abiding force of workingmen. Neither capital nor labor is like an immaterial soul that can live apart from its body. Each consists of a permanent body with a shifting composition. A permanent sum, on the one hand, a permanent amount of working energy, on the other, are always present, but they are in goods and men respectively. Each may well be described by the use of an abstract term, and in practical life it commonly is so; but it is a concrete reality. _Peculiarity of Land as a Capital Good._--One reservation needs to be made when we call capital goods perishable. If we include land under this term, we must make it an exception to the rule of destructibility. It is the only thing that does not go out of existence in the using. It is not a produced good at all and does not stand, like other goods, in an intermediate position between labor and the gratification that labor is intended to produce. Work did not create it and using will not end it. It will be called, in our study, a capital good, for it is a form of wealth which produces other wealth. It enters into the permanent productive fund that society is using. _Differences between Land and Other Capital Goods Important in Economic Dynamics._--It is in a later part of the study which deals with economic changes--the part which we shall call Economic Dynamics--that the differences between land and artificially made goods become prominent, and these differences will receive due emphasis in their proper place. In studying the law which would govern economic society if no essential economic changes were taking place,--in reducing society, as it were, to a static state,--we find that there is a certain set of characteristics which land shares with those capital goods which are the products of human industry. In static studies it is best to group the productive instruments which men make with the one unmade good which nature furnishes and to recognize that together they embody the permanent fund of productive wealth.[4]