payment which are not in any way commodities of exchange in the proper sense of the term. “Exchange-commodity ” is therefore not the wider concept we are seeking.
If, however, we say conversely, “Every exchange-commodity is a means of payment,” we have not got what we wanted. There are exchange-commodities which are not means of payment.
If one man exchanges corn for another's silver, the silver is an exchange-commodity for the one, corn an exchange-commodity for the other, within this one transaction.
In this wide sense the concept “Exchange-commodity” does not yet serve our purpose; it remains uncertain whether the exchange-commodity is a means of payment. And this cannot be asserted either of silver or of corn, so long as we look only to one transaction.
When, however, in any society, for example, a State, it is a custom gradually recognised by law that all goods should be exchanged against definite quantities of a given commodity, e.g. silver, then in this instance silver has become an exchange-commodity in a narrower sense. It is called, therefore, within the range of its use, a general exchange-commodity. The general exchange-commodity is, accordingly, an institution of social intercourse; it is a commodity which has obtained a special use in society, first by custom, then by law.
