164 MODERN MONETARY SYSTEMS 
enable transactions to be carried out without any move- 
ment of bullion by a mere process of accounting. Thus 
it is easy to lose sight of the fact that this unit of account 
is often synonymous with a given weight of a certain metal,! 
so that the commodities which are to be exchanged are 
no longer compared mentally with this given quantity 
of metal, but with the unit of account itself, behind which 
there is seen dimly a whole series of commodities of a 
value which is equivalent or lower or higher. A teacher 
who is paid 20 francs for a lesson sees that the lesson 
represents two or three meals or a hat or a whole set of 
objects which may be obtained for 20 francs, or for some 
multiple or sub-multiple of this sum. A small shop- 
keeper who has made a profit of §o francs in the course of 
his day’s work sees in it the possibility of feeding his 
family for some days on this sum, or of paying a certain 
part of his rent, etc.? 
1 It should be remembered, however, that before the French Revolution 
a money of account like the livre was different from real currencies such 
as the écu or the louis, and that these real currencies corresponded to 
varying numbers of units of account according to whatever scale was in 
force at the moment. 
2 M. Bourguin in his study “La mesure de la valeur et la monnaie,” Revue 
& économie politique, 1895, pp. 408 et seq., while he recognises that owing 
to the diversity of commodities the abstract idea of money as a measure of 
values ends by becoming detached from the objects into which the instru- 
ment of exchange (gold, paper, silver, etc.) is transformed, believes that it 
is possible to put into circulation a currency of which the unit does not 
correspond to a given quantity of a given commodity, and concludes that 
“it is essential that the conception of a unit of measure should be related to 
some concrete object.” 
This remark seems to us to be true only as a matter of history. But once 
the monetary unit which was originally connected with a given commodity 
is in circulation, the person who receives or gives it does not find it any 
easier to grasp the exchange value of a piece of precious metal than that of 
an abstract unit of account. Therefore when we come to study value we are 
forced to distinguish between value in barter where each commodity has 
its own utility, and value in exchange for money where we only have to 
take into consideration the utility of the commodity as estimated by the 
purchaser. Indeed a person who gives or receives money does not appear 
capable of realising the value of this amount of commodities, even by 
referring to the commodity in which the money was originally incorpor- 
ated, whereas he can appreciate the sum of money which he gives or 
receives as constituting a given proportion of income or capital.