(2) The 'economy of exchange' resulted in the 'degradation' of labour to a commodity, the labour wage being determined as an item of expenditure (_Eichmann's der Arbeit_) instead of representing a fixed rate of the national product. By a daring jump in history, Rodbertus derives his wages law indirectly from slavery and regards the specific traits which a capitalist production of commodities imposes on exploitation as no more than a lying deception against which he fulminates from a moral point of view. 'So long as the producers themselves remained the property of those who were not producing, so long as slavery was in existence, it was the advantage of the "masters" alone which unilaterally determined the volume of this share (of the workers). With the producers attaining full liberty of person, if nothing more as yet, both parties agree on the wage in advance. The wage, in modern terminology, is the object of a "free contract", that is to say, an object of competition. Labour is therefore as a matter of course subjected to the same laws of exchange as its products: labour itself acquires exchange value; the size of the wage depends on the effects of supply and demand.' Rodbertus, after having thus turned everything upside down, after deriving the exchange value of labour from competition, now immediately derives its value from its exchange value. 'Under the laws of exchange value, labour, like produced goods, comes to have a kind of "cost value" which exercises some magnetic effects upon its exchange value, the amount of the labour wage. It is that particular amount of payment which is necessary for the "maintenance" of labour, in other words, which enables labour to continue, if only in the persons of its progeny--it is the so-called "minimum of subsistence".' For Rodbertus, however, this is not a statement of objective economic laws, but merely an object for moral indignation. He calls the thesis of the classical school, that labour is worth no more than the wages it can command, a 'cynical' statement, and he is determined to expose the 'string of lies' leading to this 'crude and unethical' conclusion.[244] 'It was a degrading view to estimate the wages of labour in accordance with the "necessary subsistence", like so many machines to be kept in repair. Now that labour, the fountainhead of all commodities, has itself become a commodity of exchange, it is no less degrading to speak of its "natural price", of its "costs", just as we speak of the natural price and costs of its product, and to include this natural price, these costs, in the amount of goods that is necessary to call forth a continuous flow of labour on the market.'