Before money: the trouble with swapping
Long before coins, people simply traded one thing for another. It worked — until it really didn't.
In a barter world you swap what you have for what you want. But for any deal to happen, the other person must want exactly what you're offering, right now, in the right amount. Economists call this the double coincidence of wants — and it makes trade slow, clumsy, and often impossible. Money fixes it by being one thing everybody accepts.
Why swapping breaks down
The catch
A perfect match
Both sides must want what the other offers, at the same time. Rare.
Worse still
Fish rots
You can't save your wealth as fish for next year — it spoils.
Every man thus lives by exchanging, and the society itself grows to be what is properly a commercial society.Adam Smith, The Wealth of Nations