1 The General Economic Conditions for the Use of Money
Where the free exchange of goods and services is unknown, money is not wanted. In a state of society in which the division of labor was a purely domestic matter and production and consumption were consummated within the single household it would be just as useless as it would be for an isolated man. But even in an economic order based on division of labor, money would still be unnecessary if the means of production were socialized, the control of production and the distribution of the finished product were in the hands of a central body, and individuals were not allowed to exchange the consumption goods allotted to them for the consumption goods allotted to others.
The phenomenon of money presupposes an economic order in which production is based on division of labor and in which private property consists not only in goods of the first order (consumption goods), but also in goods of higher orders (production goods). In such a society, there is no systematic centralized control of production, for this is inconceivable without centralized disposal over the means of production. Production is “anarchistic.” What is to be produced, and how it is to be produced, is decided in the first place by the owners of the means of production, who produce, however, not only for their own needs, but also for the needs of others, and in their valuations take into account, not only the use-value that they themselves attach to their products, but also the use-value that these possess in the estimation of the other members of the community. The balancing of production and consumption takes place in the market, where the different producers meet to exchange goods and services by bargaining together. The function of money is to facilitate the business of the market by acting as a common medium of exchange.
2 The Origin of Money
Indirect exchange is distinguished from direct exchange according as a medium is involved or not.
Suppose that A and B exchange with each other a number of units of the commodities m and n. A acquires the commodity n because of the use-value that it has for him. He intends to consume it. The same is true of B, who acquires the commodity m for his immediate use. This is a case of direct exchange.
If there are more than two individuals and more than two kinds of commodity in the market, indirect exchange also is possible. A may then acquire a commodity p, not because he desires to consume it, but in order to exchange it for a second commodity q which he does desire to consume. Let us suppose that A brings to the market two units of the commodity m, B two units of the commodity n, and C two units of the commodity o, and that A wishes to acquire one unit of each of the commodities n and o, B one unit of each of the commodities o and m, and C one unit of each of the commodities m and n. Even in this case a direct exchange is possible if the subjective valuations of the three commodities permit the exchange of each unit of m, n, and o for a unit of one of the others. But if this or a similar hypothesis does not hold good, and in by far the greater number of all exchange transactions it does not hold good, then indirect exchange becomes necessary, and the demand for goods for immediate wants is supplemented by a demand for goods to be exchanged for others. 
Indirect exchange becomes more necessary as division of labor increases and wants become more refined. In the present stage of economic development, the occasions when direct exchange is both possible and actually effected have already become very exceptional. Nevertheless, even nowadays, they sometimes arise. Take, for instance, the payment of wages in kind, which is a case of direct exchange so long on the one hand as the employer uses the labor for the immediate satisfaction of his own needs and does not have to procure through exchange the goods in which the wages are paid, and so long on the other hand as the employee consumes the goods he receives and does not sell them. Such payment of wages in kind is still widely prevalent in agriculture, although even in this sphere its importance is being continually diminished by the extension of capitalistic methods of management and the development of division of labor. 
Thus along with the demand in a market for goods for direct consumption there is a demand for goods that the purchaser does not wish to consume but to dispose of by further exchange. It is clear that not all goods are subject to this sort of demand. An individual obviously has no motive for an indirect exchange if he does not expect that it will bring him nearer to his ultimate objective, the acquisition of goods for his own use. The mere fact that there would be no exchanging unless it was indirect could not induce individuals to engage in indirect exchange if they secured no immediate personal advantage from it. Direct exchange being impossible, and indirect exchange being purposeless from the individual point of view, no exchange would take place at all. Individuals have recourse to indirect exchange only when they profit by it; that is, only when the goods they acquire are more marketable than those which they surrender.
The theory of money must take into consideration all that is implied in the functioning of several kinds of money side by side. Only where its conclusions are unlikely to be affected one way or the other, may it proceed from the assumption that a single good is employed as common medium of exchange. Elsewhere, it must take account of the simultaneous use of several media of exchange. To neglect this would be to shirk one of its most difficult tasks.
3 The “Secondary” Functions of Money
The simple statement, that money is a commodity whose economic function is to facilitate the interchange of goods and services, does not satisfy those writers who are interested rather in the accumulation of material than in the increase of knowledge. Many investigators imagine that insufficient attention is devoted to the remarkable part played by money in economic life if it is merely credited with the function of being a medium of exchange; they do not think that due regard has been paid to the significance of money until they have enumerated half a dozen further “functions”—as if, in an economic order founded on the exchange of goods, there could be a more important function than that of the common medium of exchange.
This applies in the first place to the function fulfilled by money in facilitating credit transactions. It is simplest to regard this as part of its function as medium of exchange. Credit transactions are in fact nothing but the exchange of present goods against future goods. Frequent reference is made in English and American writings to a function of money as a standard of deferred payments.  But the original purpose of this expression was not to contrast a particular function of money with its ordinary economic function, but merely to simplify discussions about the influence of changes in the value of money upon the real amount of money debts. It serves this purpose admirably. But it should be pointed out that its use has led many writers to deal with the problems connected with the general economic consequences of changes in the value of money merely from the point of view of modifications in existing debt relations and to overlook their significance in all other connections.
The functions of money as a transmitter of value through time and space may also be directly traced back to its function as medium of exchange. Menger has pointed out that the special suitability of goods for hoarding, and their consequent widespread employment for this purpose, has been one of the most important causes of their increased marketability and therefore of their qualification as media of exchange.  As soon as the practice of employing a certain economic good as a medium of exchange becomes general, people begin to store up this good in preference to others. In fact, hoarding as a form of investment plays no great part in our present stage of economic development, its place having been taken by the purchase of interest-bearing property.  On the other hand, money still functions today as a means for transporting value through space.  This function again is nothing but a matter of facilitating the exchange of goods. The European farmer who emigrates to America and wishes to exchange his property in Europe for a property in America, sells the former, goes to America with the money (or a bill payable in money), and there purchases his new homestead. Here we have an absolute textbook example of an exchange facilitated by money.
Particular attention has been devoted, especially in recent times, to the function of money as a general medium of payment. Indirect exchange divides a single transaction into two separate parts which are connected merely by the ultimate intention of the exchangers to acquire consumption goods. Sale and purchase thus apparently become independent of each other Furthermore, if the two parties to a sale-and-purchase transaction perform their respective parts of the bargain at different times, that of the seller preceding that of the buyer (purchase on credit), then the settlement of the bargain, or the fulfillment of the seller’s part of it (which need not be the same thing), has no obvious connection with the fulfillment of the buyer’s part. The same is true of all other credit transactions, especially of the most important sort of credit transaction—lending. The apparent lack of a connection between the two parts of the single transaction has been taken as a reason for regarding them as independent proceedings, for speaking of the payment as an independent legal act, and consequently for attributing to money the function of being a common medium of payment. This is obviously incorrect. “If the function of money as an object which facilitates dealings in commodities and capital is kept in mind, a function that includes the payment of money prices and repayment of loans…there remains neither necessity nor justification for further discussion of a special employment, or even function of money, as a medium of payment.” 
The root of this error (as of many other errors in economics) must be sought in the uncritical acceptance of juristical conceptions and habits of thought. From the point of view of the law, outstanding debt is a subject which can and must be considered in isolation and entirely (or at least to some extent) without reference to the origin of the obligation to pay. Of course, in law as well as in economics, money is only the common medium of exchange. But the principal, although not exclusive, motive of the law for concerning itself with money is the problem of payment. When it seeks to answer the question, What is money? it is in order to determine how monetary liabilities can be discharged. For the jurist, money is a medium of payment. The economist, to whom the problem of money presents a different aspect, may not adopt this point of view if he does not wish at the very outset to prejudice his prospects of contributing to the advancement of economic theory.
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