“standard of value.” It is, perhaps, better expressed by F. A. Walker223 as a “standard of deferred payments.” Its existence is due to the desire to have a means of comparing the purchasing power of a commodity at one time with its purchasing power at another distant time; that is, that for long contracts, exchanges may be in unchanged ratios at the beginning and at the end of the contracts. There is no distinction between this function and the first, except one arising from the introduction of time. At the same time and place, the “standard of value” is given in the common denominator of value.
A Measure of Value,224 in the ordinary sense of the word measure, would mean something by comparison with which we may ascertain what is the value of any other thing. When we consider, further, that value itself is relative, and that two things are necessary to constitute it, independently of the third thing which is to measure it, we may define a Measure of Value to be something, by comparing with which any two other things, we may infer their value in relation to one another.
In this sense, any commodity will serve as a measure of value at a given time and place; since we can always infer the proportion in which things exchange for one another, when we know the proportion in which each exchanges for any third thing. To serve as a convenient measure of value is one of the functions of the commodity selected as a medium [pg 289] of exchange. It is in that commodity that the values of all other things are habitually estimated.
But the desideratum sought by political economists is not a measure of the value of things at the same time and place, but a measure of the value of the same thing at different times and places: something by comparison with which it may be known whether any given thing is of greater or less value