Capital, Volume Three: The Process of Capitalist Production as a Whole by Karl Marx

In the analysis of ground-rent we shall begin with the assumption that products paying such a rent, products in which a portion of the surplus-value, and therefore also a portion of the total price, resolves itself into ground-rent, i.e., that agricultural as well as mining products are sold at their prices of production like all other commodities. (It suffices for our purposes to confine ourselves to agricultural and mining products.) In other words, their selling prices are made up of the elements of their cost (the value of consumed constant and variable capital) plus a profit determined by the general rate of profit and calculated on the total advanced capital, whether consumed or not. We assume, then, that average selling prices of these products are equal to their prices of production. The question now arises how it is possible for ground-rent to develop under these conditions, i.e., how it is possible for a portion of the profit to become transformed into ground-rent, so that a portion of the commodity-price falls to the landlord.

In order to demonstrate the general character of this form of ground-rent, let us assume that most of the factories of a certain country derive their power from steam-engines, while a smaller number derive it from natural waterfalls. Let us further assume that the price of production in the former amounts to 115 for a quantity of commodities which have consumed a capital of 100. The 15% profit is calculated not solely on the consumed capital of 100, but on the total capital employed in the production of this commodity-value. We have previously shown that this price of production is not determined by the individual cost-price of every single industrial producer, but by the average cost-price of the commodity under average conditions of capital in the entire sphere of production. It is, in fact, the market-price of production, the average market-price as distinct from its oscillations. It is in general in the form of the market-price, and, furthermore, in the form of the regulating market-price, or market-price of production, that the nature of the value of commodities asserts itself, its determination not by the labour-time necessary in the case of any individual producer for the production of a certain quantity of commodities, or of some individual commodity, but by the socially necessary labour-time; that is, by the labour-time, required for the production of the socially necessary total quantity of commodity varieties on the market under the existing average conditions of social production