A bill carries a promise across place and time
In the later Middle Ages, the bill of exchange became important to long-distance trade. A merchant supplied value to a banker in one place, and a named recipient received an agreed sum in another city at a later date, often in another currency. The paper carried an instruction and obligation, not transported metal.
Research into the fifteenth-century Borromei ledgers shows bills being used flexibly for transfers, credit, instalments and security for other contracts. They depended on correspondent networks, accounts, reputation and legal enforceability.
A deposit becomes a payment instrument
When people leave coin or bullion with a trusted custodian, they receive a claim for return. Payment can occur by reassigning part of the balance from one account to another. The physical asset stays in place while its accounting attribution changes.
When recipients accept the bank's obligation, a deposit performs a monetary function. It is an asset to the customer and a liability of the bank. Payment quality therefore depends on solvency, liquidity, records and rules for settlement among banks.
- cash is a held means of payment
- a deposit is a claim on a bank
- a deposit transfer changes bank records
- interbank settlement discharges obligations among institutions
Banks were not invented in one day
Custody, coin exchange, lending, account-keeping and trade finance developed in different cities and institutions. Not every money changer was a bank in today's sense, and not every early bank performed all modern banking activities.
Modern banking emerged as these functions combined with law, central clearing, supervision and deposit protection. Seeking one inventor of banking would be as misleading as seeking one inventor of money.
From bank liabilities to Bitcoin
Modern card and bank payments are convenient because institutions keep accounts, connect networks and correct some errors. The user nevertheless holds a claim, and access can depend on the bank, its rules and operational availability.
Bitcoin enables asset transfer without a bank liability when users control their keys and the network verifies the transaction. It does not automatically supply credit, reversal of mistaken payments or customer support. Banking history explains why intermediaries arose; Bitcoin shows which operations may be performed without them.