In the marginal utility scheme above outlined there is no place for money, on the assumptions laid down. It is a scheme of barter relations. The utilities which come into equilibrium are not subjective-exchange-values, which, as Schumpeter, with Wieser, contends, are the only subjective values money has, but are real subjective use values--marginal utilities. The scheme, assuming as it does, perfect exchangeability of all goods, with infinitesimal increments in consumption, has no place for money. There really is no money service to be performed. Schumpeter, indeed, speaks of money as a mere "Schleier," which does not touch the essence of the phenomena, and such it is on his assumptions. In a similar situation, Professor Irving Fisher gives up the effort to find a psychological explanation of the value of money,[93] and offers the quantity theory as a mechanical principle, additional to the psychological barter scheme. Schumpeter, however, does lip service still to the need for a psychological explanation. His answer runs in Wieser's terms--indeed, he attributes it to Wieser. The _Preis_ of money[94]--Schumpeter does not use Wieser's absolute value concept, but lets his value of money run in purely relative terms--the price of money in goods depends on the subjective value of money. This subjective value of money rests on the experience of each individual in making purchases--rests on the prices of consumption goods, determined by the relation between real income and money income. The circle is as clear as day.