This seems a little confusing. The amount of new value created and
incorporated into output over a given period is the equivalent of the
wage-payments (variable capital) outlaid PLUS the surplus-value (gross
profits). The "new value added", or the new value product, is V+S, not
just V.
Marx draws the distinction between constant and variable capital according
to whether the capital undergoes a quantitative alteration of value in the
production process. This distinction made in defining the valorisation
process corresponds to the objective and subjective factors of the labour
process - the human subject is the creator of value, even though it
confronts people as an "objective force", as "the market".
Marx notes that the definition of constant capital "by no means excludes
the possibility of a change of value in its elements... if the amount of
labourtime socially necessary for the production of any commodity alters...
this reacts back on all the commodities of the same type... and their value
at any given time is measured ... by the labour necessary under the social
conditions existing at the time." (section on constant and variable
capital, Penguin edition C1, ch. 8).
The measure of variable capital is the current reproduction cost of labour
power, and it is this which varies within physiological, moral and
historical limits. Thus, the magnitude of variable capital is a result, an
outcome of a series of factors which interact with each other to produce
accepted norms for the "cost of living".
Regards
Jurriaan.