Through all this analysis, marx establishes the conceptual categories of value and exchange value, deriving them as real abstractions from the actual process of capitalist production and exchange. He stresses that each commodity constitutes a dialectical unity of its use value and its value, which is determined by the quantity of socially necessary abstract labour required for its production (marx 1975, ii: 42). These commodity values are necessarily expressed, through the monetary intermediation, into commodity prices in the market. While commodity values themselves are produced in the sphere of production, these commodities have to be sold in the market and thus the labour expended for their production to be socially ratified through the realization of production. in this sense, the dialectical unity between production and exchange has to be taken into account, within the context of the overall capitalist reproduction, for the precise valuation of commodities.