The oldest advice is about the other party

One rule, three thousand years

Read the household books of three thousand years in order and one rule appears in every century. It is not "spend less than you earn", though that is there too. It is this: the person on the other side of your money may not be honest, so keep a record that does not depend on their word.

The rule is older than coins. The Babylonian code says that goods handed over "without witness or contract" carry "no legitimate claim".¹ Hesiod, about 700 BC, tells his reader to get a witness even when dealing with a brother, "for trust and mistrust, alike ruin men".² A Jewish wisdom book puts it in five words: "when you give or receive, put it all in writing."³

The steward who wasted the goods

The other party is not always a stranger. Often it is the person you pay to handle your money. Xenophon's farmer tests his bailiff for honesty and admits it is the hardest thing to teach.⁴ Cato's overseer may give no credit, lend nothing and hide nothing from the master.⁵ In the Gospel of Luke a rich man is told that his steward has wasted his goods, and the steward is called in with the words "give an account of thy stewardship".⁶ Thirteen centuries later Walter of Henley warns that servants "make merchandise with their lord's money to their own profit", and prescribes an annual view of account by someone the owner trusts.⁷

None of these writers thought stewards were uniquely wicked. They thought that anyone who handles money that is not theirs will handle it better when the owner looks. Xenophon called it "the master's eye".⁸

Agree the price first

The Paris householder of 1393 tells his steward to bargain with workmen "before they set hand to the work, that there may be no dispute afterwards".⁹ Walter of Henley wants a "true man or two" to witness every purchase and sale.⁷ Thomas Aquinas rules that a seller who hides a defect makes the sale "illicit and fraudulent".¹⁰ The price, the terms and the condition of the goods were to be fixed and known before money changed hands. What was hidden was fraud, in canon law, six centuries before consumer protection.

The lender's memory

Benjamin Franklin's contribution, in 1758, was to notice which side keeps the better records: "Creditors have better memories than debtors."¹¹ The party who is owed money writes it down. The party who owes tends not to. That asymmetry is the whole reason the old writers insisted the household keep its own books.

"Buyer beware" is not Roman

One phrase seems to cut the other way. Caveat emptor, "let the buyer beware", is usually taken as ancient wisdom that the buyer is on his own. It is not ancient. It is an English legal maxim first recorded around 1534, and by one scholarly argument it "never had any place in Roman law".¹² The medieval rule was the opposite: the seller had to disclose. The buyer-beware rule is a modern invention, and it was invented by sellers' lawyers. The Statute of Frauds of 1677 pulled the other way again, requiring guarantees of another's debt to be in writing.¹³

The other party today

Every household still deals with an other party. Today it is an insurer, a lender, a broker, an adviser, a card network or an employer, and each one keeps the record and presents the account. That is exactly the arrangement the old books warned against. The steward keeps the books and the owner does not look.

The modern form of the witness is the household's own record, kept in its own words. Plenee's three statements exist for that purpose. FLOW: the 3 states every window of money ends in is the record of what moved. NET: did you come out ahead? is the reckoning of whether the period came out ahead. NEST: what you actually own is the list of what you own, counted and written down, as Ischomachus did with his wife in Athens. And the question to ask of every counterparty is the one this whole track has been asking: what did I give, what did I get back, and who holds the record?

Hesiod would have told you to get a witness. This is how you become your own.