We can not validly study economy without appeal to a landmark and to an exchange reference measure, in the same way that in all science, the considered landmark and measure units should be define before a study.
As a reference and time units and length units are necessary to the establishment of physics laws, no advanced study can be conducted without the previous definitions of the economy reference frame and the associated measure unit.
An economic zone or a monetary zone is the base frame of the economic study. What characterizes it?
The space where the monetary agreement is manifest
Time, that is to say, the average life span of individuals who live and die in it.
Individual or collective (entrepreneurial) production of goods and services
The exchange of goods and services between individuals or groups of individuals.
Individuals or groups of individuals are inevitably brought to exchange, even if only information, education, or even more generally bonds. What therefore fundamentally characterizes the economic zone is all the individuals who compose it. The economy exist everywhere and at all times as soon as individuals produce and exchange goods and services, and that regardless of the nature of these goods and services. On the other hand, we cannot define an economic zone empty of individuals. Therefore it is indeed the individual who constitutes the only common and fundamental value of any valid economic frame.
But to go further, this set of individuals evolve in time with births and deaths, immigration and emigration. Therefore the economic zone can be seen as a discretized spacetime in constant creation/destruction where each temporary point represents an individual with a limited life span.
Thus it is a spatiotemporal model in continuous, non-static, discreet transformation, where each space-time point is created at a determined date (birth of an individual) and has a limited duration which, on average, matches to the life span which we will denote “ls” in the considered economic zone.
Furthermore and this is the fundamental definition of Relativity in economics, any individual has a personal and unique vision of the value of all things and no individual or groups of individuals from an economic zone is to be able to impose onto others a particular vision of what is value or not.
An economic zone is said to be pseudo-isolated when, for a given time duration, we can consider that it lives independently or quasi-independently from its exterior. It could be the case of economies on still autonomous islands, where the livelihoods of individuals is ensured by sufficient food production (which is also quite relative, see for example the case study of some ascetics), but also the case of a topologically complex group of individuals in a non-connected, transnational, even transcontinental space. As long as it shows autonomy, we can consider it as a pseudo-isolated economic zone, able to self-manage its flow of production and exchange, at least on a small period of time.
When there is exchange of goods and/or services, we talk about value exchange. X exchanges with Y a value Vx = Vy = Px × Cx = Py × Cy, where “Px” represents the price in the common measure unit (called the common money) of X’s production “Cx”.
This definition of value is perfectly relative to the observer who measures it, so if X considers that Vx = Vy, it is possible that Y considers Vy >> Vx, and be perfectly fine. Furthermore, Z who observed this exchange may well judge according to his own referential that Vx and Vy does not have any value.
Recall here how much men are fundamentaly not agreed all long of their history on respective value of their goods. Also equality of exchange values is not an independent economic criterion of the observer, which is also seen by the actions of donations ou taxation withou returns, and therefore non-symetrics, where equality of exchange values is not respected according the point of view.
This is for universals needs of value measure, that individuals agree on a common measure of exchange they call money. A define money give thus a common measure of value to all things in same unity, for a given observation landmark, which permits comparisons wealthier.
Money thus act not only of exchange tool between individuals of an economic zone, but also the only value independent from the observation landmark.
This being said, it exit historically and locally, a many different definitions of money, which involved fundamentally different types of exchanges, and which are often ignored by those which accepts to use it.
Those cases of ignorance of money nature used most of the time in a constraint way, are a violation of the contractual law of the economy basis, which suppose the acceptance of involved parts about the proposed exchange type.
We can without hesitation declare that the imposition of use of a non contractual money (not subject to a voluntary acceptance) is an act opposite to human right to dispose of his life for an economic part and a violation to constitutionals principles of liberty and equality.
And thus minimum in a real democracy, the official money can not really be acceptable only if it subject of a democratic elaboration in it definition, as in it validation, it acceptation it modification and it abandonment.