Money (n.) A token representing a share in a social contract between state and citizen.
The oldest social contract, after men and women decided to specialize, she in pink and he in red, is that of the protection offered by the state in return for citizenship. The state, as neutral arbiter, offers a way out of traditional cycles of revenge violence. When regulating trade, the state promotes liquidity of goods and services by issuing "currency" tokens.
Universally, the value of a currency is a measure of the quality of the social contract, in terms of its fairness and effect in generating wealth. Bad rulers will debase their currencies to steal from their own citizens. Good rulers will do the opposite: promote their currencies by unflinching adherence to the Law and its institutions.