Just two brief comments on Riccardo's 565:
(1) I like very much his formulation, "Marx's value is a category
that arises at the meeting point of production and exchange." What
does this mean, more exactly? I think, that value can only be
understood dynamically; this is the meaning of a concept like
"realization," which R. criticizes not without reason as misleading.
What Marx is concerned to analyze is the continuous process of the
accumulation of capital: the unity of production and circulation. A
given act of labor may turn out not have constituted value
production, when the goods produced are not sold. Over time, however,
the value-form functions to represent and organize the production
process (which is simultaneously an exploitation process); that
capital accumulates signals the "realization" of value and surplus
value.
(2) It is not obvious to me that the labor producing the money
commodity is "immediately social." Mney, as a commodity, must also
function in exchange to be an incarnation of social labor. For
instance, if I transform some coins into a necklace, or melt them
down to make a toy for my child's use, the labor that produced them
turns out not to have been money-producing labor. Money represents
the social character of labor, in a disguised form. But its social
character is no more "immediate" than any other object's; it requires
mediation, i.e. use as money.
Or so it seems to me.
Paul M.