XVII. INDIRECT EXCHANGE
1. Media of Exchange and Money
Interpersonal exchange is called indirect exchange if, between the commodities and services the reciprocal exchange of which is the ultimate end of exchanging, one or several media of exchange are interposed. The subject matter of the theory of indirect exchange is the study of the ratio of exchange between the media of exchange on the one hand and the goods and services of all orders on the other hand. The statements of the theory of indirect exchange refer to all instances of indirect exchange and to all things which are employed as media of exchange.
A medium of exchange which is commonly used as such is called money. The notion of money is vague, as its definition refers to the vague term "commonly used." There are borderline cases in which it cannot be decided whether a medium of exchange is or is not "commonly" used and should be called money. But this vagueness in the denotation of money in no way affects the exactitude and precision required by praxeological theory. For all that is to be predicated of money is valid for every medium of exchange. It is therefore immaterial whether one preserves the traditional term theory of money or substitutes for it another term. The theory of money was and is always the theory of indirect exchange and of the medium of exchange.
. The theory of monetary calculation does not belong to the theory of indirect exchange. It is a part of the general theory of praxeology.