§ 5. Factors influencing individual monetary demand. In this conception of the individual monetary demand must, however, be included not merely the demands of retail purchasers, made by themselves, but also those of all agencies, such as merchants, bankers, and transportation companies, serving the needs of ultimate consumers of goods. The use of money may be necessary several times before a commodity completes its journey from producer to consumer.

Of two persons whose expenditures of money are of the same kind and made at the same rate, the one having the larger amount of purchases to make has the larger monetary demand. But the amount of purchases does not always vary directly with the amount of real income;3 for example, a farmer and a village mechanic may have at their disposal incomes equal in the quantities of goods, such as food, fuel, clothing, and house-uses (worth, let us say, $1000 for each), but the farmer would be getting a larger part of his goods directly from his farm and by his own labor, while the mechanic would be getting first a money income to be expended afterward for food, clothing, and rent. The mechanic would in this case have an average monetary demand much larger than the farmer.

We see thus that the individual monetary demand at any time is that amount of money which rests in his possession as the necessary condition to making his purchases as he desires. Individual monetary demand varies in proportion directly to the delay, and inversely to the rapidity with which the individual passes the money on; and directly to the amount of the person's income that is received and expended in monetary form.

§ 6. Concept of the community's monetary demand. The monetary demand of a community at a given time is the sum of the monetary demands of the various individuals and enterprises. It is that stock of money which is necessarily present to effect the exchanges of the community in the prevailing manner at any given level of prices. A single dollar as it circulates helps to supply the monetary demand of many individuals in turn: the more quickly each person spends the piece of money he receives, the greater its rapidity of circulation. Let us suppose that every piece of money passed from one person to another once each day. Then a dollar would, in the course of a business year (about 300 days), serve to buy (and at the same time to sell) $300 worth of goods. If the average purchases of each individual amounted to $1000 a year, the average monetary demand of each would be about $3.33 1/3.

3 See on kinds of income, Vol. I, p. 26 ff.

The times of maximum monetary demand of the different individuals do not coincide; often they alternate with each other, and the community's total monetary demand at a given time is a composite of the many individual variations. The amount of money that will remain in circulation in a community depends on several factors, the chief among them being the amount of goods to exchange, the methods of exchange, and the value of the commodity material in other uses. The amount of goods to be exchanged may change even when the amount produced is unaltered (e. g., a change from agricultural to industrial conditions). The methods of exchange may alter so as to require either more money (e. g., cash instead of credit business) or less money (e. g., use of bank checks displacing use of money by individuals). Or, apart from the other factors, the scale of prices may change as the conditions of commodity money production are altered.

§ 7. Quantity of money and prices. Consider the effect of a large and rapid increase in the production of gold in a community where the gold dollar is the standard commodity money. At first some few men, the miners, may have far more dollars than before, while most men have nearly the same number as before. But those nearest the miners and selling to them will get more dollars, which they will pass on to others, and thus, in ever-widening circles, the increased supply of gold will spread until a new equilibrium of the monetary value is attained, when every one will have got his due proportion of the new supplies. If the number of dollars has been doubled, every one will, in the long run, and "other things being equal," have twice as many dollars as before.

Now, prices of goods cannot remain the same as before; for if they did there would be twice as many pieces of money available to effect the same number of trades at the same prices. There is no reason why each person should tie up twice as large a proportion of his income in the form of money. If, however, there is a concerted movement to spend the surplus money, there results a general bidding down of the value of money, a general bidding up of the prices of goods and of services. At what point will this movement stop ? The rational conclusion must be that, other things being equal, the new equilibrium will be established when the ratio between the value of money and the price of the goods that each individual is purchasing becomes the same as before. The money in a community being doubled, prices must be doubled, and proportionally for any other change in the quantity.

§ 8. The quantity theory of money. This explanation of the effect of changes in the quantity of money in a country upon prices (the general scale of prices) is known as the quantity theory of money. This theory has, for a century, been very generally accepted by competent students of the money problem. It may be summed up thus: other things being equal, the value of the monetary unit, expressed in terms of all other commodities, falls as the quantity of money increases, and vice versa. That is, prices rise and fall in direct proportion to changes in the total quantity. This is a simple explanation of a complex and difficult set of conditions. The phrase, "other things being equal," betokens the statement of a tendency where there are several factors. The quantity theory explains what happens when there is a change in one of the factors - the number of pieces of money. There are three large sets of facts to be brought into relationship with each other in the quantity theory:

(1)  the amount of business, or the number of trades effected;

(2)   the rapidity of circulation, depending on the methods by which business is done; (3) the amount of money available. According to the quantity theory, we must expect that, when conditions (1) and (2) remain fixed, prices (the general price level) will vary directly, and the value of money will vary inversely as the quantity of money. This quantity theory may be expressed in the formula P = M/R when MR N P is the symbol for price, or the general price level, N is (1) above, R is (2), and M is (3). P, therefore, changes directly with either M or R, or inversely with N.4