have at best a potential or hypothetical price. But for Marx prices are formed according to pre-existing product-values which are socially established prior to their exchange. Marx sought to theorise the transformation of commodity values into prices of production within capitalism dialectically, as a "moving contradiction": namely, in capitalism, the value of a commodity output produced encompassed both the equivalent of the cost of the used inputs which were initially bought to produce it, as well as a gross profit component (surplus value) which became definite and manifest only after the commodity has been sold and paid for, and after costs were deducted from sales. Value was, as it were, suspended between the past and the future. An output with a certain value was produced, but exactly how much of that value would be subsequently realised upon sale in markets was usually not known in advance. Yet, that potential value also strongly affected the sales income that producers could get from it, and moreover that value was determined not by individual enterprises, but by all enterprises producing the same type of output for a given market demand ("the state of the market"). The business results of each enterprise were influenced by the overall effects created by all enterprises through their productive activity, as an ongoing process. This simple "market reality" has stumped many of Marx's interpreters though; they fail to see that value is conserved, transferred and added to by living labor, between the initial purchase of inputs with money on the one side, and the subsequent sale of outputs for more money, on the other. They see only input prices and output prices, or cost-prices and sale-prices, and not the creation of a product which already has a value prior to being exchanged at a certain price - a value which is moreover socially determined by a group of enterprises together, and which sets limits for price fluctuations. For that reason, the whole process of the formation of value which Marx so carefully lays out, with its complex determinants, seems like an unnecessary detour from commercial wisdom. If, however, we wish to understand the "deep structure" of market behavior, then we rapidly confront all the issues that Marx was concerned with. Relation to mainstream economics In modern neoclassical economics, exchange value itself is no longer explicitly theorised. The reason is that the concept of money-price is deemed sufficient in