ividual labor in a specified case. Nor did these writers overlook the
important differentiation between simple, unskilled labor and labor that
is highly skilled. If A in ten hours' labor produces exactly double the
amount of exchange-value which B produces in the same time devoted to
labor of another kind, it is obvious that the labor of B is not equal in
value to that of A. Quantity of labor cannot, therefore, be measured, in
individual cases, by time units. Despite a hundred passages which,
detached from their context, seem to imply the contrary, Adam Smith
recognized this very clearly, and attempted to solve the riddle by a
differentiation of skilled and unskilled labor in which he likens
skilled labor to a machine; and insists that the labor and time spent in
acquiring the skill which distinguishes skilled labor must be
reckoned.[170]

Another frequent criticism of the Marxian theory has not only been
answered by Marx himself--is, in fact, ruled out by the terms of the
theory itself--but was amply replied to by Ricardo.[171] The criticism
in question consists in the selection of what may be called "unique
values," or scarcity values, articles which cannot be reproduced by
labor, and whose value is wholly independent of the quantity of labor
originally necessary to produce them. Such articles are unique specimens
of coins and postage stamps, autograph letters, rare manuscripts,
Stradivarius violins, Raphael pictures, Caxton books, articles
associated with great personages--such as Napoleon's snuffbox--great
auks' eggs, and so on _ad infinitum_. No possible amount of human labor
could reproduce these articles, reproduce, that is to say, the exact
utilities in them. Napoleon's snuffbox might be exactly duplicated so
far as its physical properties are concerned, but the association with
Napoleon's fingers, the sentimental quality which gives it its special
utility, is not reproducible. But the trade of capitalist society does
not consist in the manufacture and sale of these things, which, after
all, form a very insignificant part of the exchange-values of the world.

III

Marx saw the soul of truth in the labor-value theory, as propounded by
his predecessors, especially Ricardo, and devoted himself to its
development and systematization. He has been accused of plagiarizing his
theory from the Ricardians, but it is surely not plagiarism when a
thinker sees the germ of truth in a theory, and, separating it from the
m