The answer to the first question rests primarily in the fact that there are differences in the _saleability_ of goods. Value and saleability are not the same thing. A copper cent has high saleability; a farm has low saleability.[457] Some valuable things cannot be exchanged at all. The Capitol at Washington cannot be exchanged, yet has value. Under a communistic or socialistic régime, exchange, as we now know it, would largely or wholly cease. An entailed estate cannot be sold, yet has value. If society should really come to the stable equilibrium of the "static state," most of the exchanges of lands,[458] securities, and other long-time income-bearers would cease, but they would still be valuable. I have developed these notions in my article on "Value" in the _Quarterly Journal of Economics_, Aug. 1915, and have referred to them again in the chapter on "Value" in the present book, and so need not expand the discussion here. Exchangeability and value are different characteristics of goods. Value is an essential precondition of exchangeability, but can exist without it. Value is, however, commonly increased by exchangeability. But the theory of exchangeability is a separate matter, and cannot be deduced from the theory of value alone.
Menger points out the difference between "buying price" and "selling price." You can buy a piano for $400. If you try the next minute to sell it for $375 you will probably fail. You may pay ten thousand dollars for a farm. The income of the farm may increase. The tax assessment may increase. The capital value of the farm may increase. And yet, you may have to wait for a long time before you find a buyer who will pay you ten thousand dollars for it. One buys pianos or farms, as a rule, only when one wishes to use them, or when one has such special knowledge of the market that one knows pretty definitely where purchasers can be found for a resale, at a profit. Even in such highly organized markets as the stock and produce exchanges, one cannot usually buy in quantity and sell immediately without some loss. "Buying price" and "selling price" of such a stock as Industrial Alcohol Preferred are sometimes five points apart, at a given time. The forced sale of land in bankruptcies, or for taxes, notoriously often bring prices far below the price which would correctly express the value of the land. It is only in the ideal fluid market assumed by static theory, where adjustments are instantaneous, where causal-temporal relations have become timeless logical relations, that values are perfectly expressed in prices.[459]