On the Origins of Money - Carl Menger
The man who goes to market with his wares intends as a rule to dispose of them, by no means at any price whatever, but at such as corresponds to the general economic situation. if we are going to inquire into the different degrees of saleableness in goods so as to show its bearing upon practical life, we can only do so by consulting the greater or less facility with which they may be disposed of at prices corresponding to the general economic situation, that is, at economic prices.(3*) A commodity is more or less saleable according as we are able, with more or less prospect of success, to dispose of it at prices corresponding to the general economic situation, at economic prices.
The interval of time, moreover, within which the disposal of a commodity at the economic price may be reckoned on, is of great significance in an inquiry into its degree of saleableness. It matters not whether the demand for a commodity be slight, or whether on other grounds its saleableness be small; if its owner can only bide his time, he will finally and in the long run be able to dispose of it at economic prices. Since, however, this condition is often absent in the actual course of business, there arises for practical purposes an important difference between those commodities, on the one hand, which we expect to dispose of at any given time at economic, or at least approximately economic, prices, and such goods, on the other hand, respecting which we have no such prospect, or at least not in the same degree, and to dispose of which at economic prices the owner foresees it will be necessary to wait for a longer or shorter period, or else to put up with a more or less sensible abatement in the price.
Again, account must be taken of the quantitative factor in the saleableness of commodities. Some commodities, in consequence of the development of markets and speculation, are able at any time to find a sale in practically any quantity at economic, approximately economic, prices. Other commodities can only find a sale at economic prices in smaller quantities, commensurate with the gradual growth of an effective demand, fetching a relatively reduced price in the case of a greater supply.