Money began as credit, not as a physical thing

Ferguson pushes back on the folk idea that money started as barter and evolved into coins and eventually paper. Instead, he traces evidence from ancient Mesopotamia showing that clay tablets recording debts predate coinage by centuries. What we call money, in his account, is fundamentally a record of trust between people: an IOU that becomes tradable once enough strangers accept it as a stand-in for future repayment.

This matters because it flips the usual moral framing of debt. If credit is the origin of money rather than a corruption of "real" money, then borrowing and lending aren't parasitic add-ons to a barter economy — they're the foundation the whole system was built on. Coins and cash came later, as portable, anonymous versions of the same underlying idea: a promise that other people will honor.

Takeaway: distrust the idea that debt is a modern deviation from honest money — debt came first.