olitical progress of society,
consciously recognized as such.

The sociological viewpoint appears throughout the whole of Marxian
economic thought. It appears, for instance, in the definition of a
commodity as the unit of wealth _in those societies in which the
capitalist mode of production prevails_. Likewise wealth and capital
connote special social relations or categories. Wealth, which in certain
simpler forms of social organization consists in the ownership of
use-values, under the capitalist system consists in the ownership of
exchange-values. Capital is not a thing, but a social relation between
persons established through the medium of things. Robinson Crusoe's
spade, the Indian's bow and arrow, and all similar illustrations given
by the "orthodox" economists, do not constitute capital any more than an
infant's spoon is capital. They do not serve as the medium of the social
relation between wage-worker and capitalist which characterizes the
capitalist system of production. The essential feature of capitalist
society is the production of wealth in the commodity form; that is to
say, in the form of objects that, instead of being consumed by the
producer, are intended to be exchanged or sold at a profit. Capital,
therefore, is wealth set aside for the production of other wealth with a
view to its exchange at a profit. A house may consist of certain
definite quantities of bricks, timber, lime, iron, and other substances,
but similar quantities of these substances piled up without plan will
not constitute a house. Bricks, timber, lime, and iron become a house
only in certain circumstances, when they bear a given ordered relation
to each other. "A negro is a negro; it is only under certain conditions
that he becomes a slave. A certain machine, for example, is a machine
for spinning cotton; it is only under certain defined conditions that it
becomes capital. Apart from these conditions, it is no more capital than
gold _per se_ is money; capital is a social relation of
production."[163]

This sociological principle pervades the whole of Socialist economics.
It appears in every economic definition, practically, and the
terminology of the orthodox political economists is thereby often given
a new meaning, radically different from that originally given to it and
commonly understood. The student of Socialism who fails to appreciate
this fact will most frequently land in a morass of confusion and
difficulty, but the carefu