Private property as de iure institution needs a foregoing state to come into existence.
The state needs foregoing power and foregoing power needs armed force.
The ultimate “foundation of the economy” thus is the weapon, where possession and property are identical ...
... because the possession of it guarantees property of it.
Armed force starts additional production (surplus, tribute).
The first taxes are contributions of material for the production of attack weapons (copper, tin).
Thus non - circulating money begins. Taxes as “census” and money are the same."
As soon as defence and protection of the (property-) title power executed by armed force in war and peace needs mercenaries (soldiers from outside the power system)...
... the one-way-money turns into circulating “genuine money” in modern sense and its material changes from weapon-fitting
... to precious metal and actually into any material which can be monopolized by the state.
Interest also at first is the tax (census) itself. The state, that must exist before property and property-based contracts ...
... which only can be executed with use of armed force, can’t be financed out of property or income which can only appear after its existence.
Therefore the state faces the problem of pre-financing itself (power, sovereignty) and it must draw on later tributes or taxes.
This “interest”, which always starts with power-based and never with “private” titles is nothing but a discount, ...
... thereby rather a discount of the state-owned property (monopoly of armed force) or property rights (monopoly of taxation) than any private “property premium” ...
... or even an mysterious item that “enlarges” something.
Interest then is the partition (cession) of forced or expected income (as measured in the state - owned monopoly to declare “legal tender”) or property (goods) ..
... by the party which will get this income or property (goods) with other parties.
The more (existing) property is ceded by the state to the private sector or can be created as income after cession to the private sector ...
.. the longer the process called “creation of wealth” (recte: later income or property) can endure, because the more power-sustaining taxes can be imposed.
Nonetheless the breakdown of all property-systems is inevitable.
This we actually can study watching the exploding indebtedness of “democratic” powers.
The problem of state power vs. private economic activities is per definitionem unsolvable.
Wealth creating inevitably sooner or later leads to wealth destruction.
This explains “rise and fall” of any power- or state-based system throughout history.