"The trade of banks is the buying and selling of interest and exchange"
About this Quote
Banks aren’t mystical vaults; they’re merchants of two prices: the price of money over time (interest) and the price of money across borders (exchange). William Petty’s line strips early modern finance down to its basic mechanics, and the austerity is the point. In a century when banking still carried the whiff of usury and foreign intrigue, Petty reframes it as plain trade. Not predation, not alchemy: commerce.
The intent is diagnostic. Petty is mapping what banks actually do, not what they claim to do. Deposits, safekeeping, even lending to kings are side narratives. The core business is dealing in spreads: borrowing cheaply and lending dear; converting currencies and clipping a margin. By naming “interest and exchange” as bank “trade,” he quietly normalizes profit in finance as something earned through price-making, not moral deviation.
The subtext is political economy with a scalpel. Petty is writing in a Britain building a fiscal-military state, where credit markets, public debt, and international payments become instruments of power. “Exchange” isn’t just tourists swapping coins; it’s the plumbing of empire, war finance, and trade deficits. If banks control exchange, they influence who can move value, when, and at what cost.
It also anticipates a modern argument: finance is not primarily about “money,” but about time and conversion. Petty’s phrasing compresses the whole sector into two levers that still govern everything from mortgages to currency crises, and in doing so, demystifies banking while warning you where its real power sits: in setting the terms.
The intent is diagnostic. Petty is mapping what banks actually do, not what they claim to do. Deposits, safekeeping, even lending to kings are side narratives. The core business is dealing in spreads: borrowing cheaply and lending dear; converting currencies and clipping a margin. By naming “interest and exchange” as bank “trade,” he quietly normalizes profit in finance as something earned through price-making, not moral deviation.
The subtext is political economy with a scalpel. Petty is writing in a Britain building a fiscal-military state, where credit markets, public debt, and international payments become instruments of power. “Exchange” isn’t just tourists swapping coins; it’s the plumbing of empire, war finance, and trade deficits. If banks control exchange, they influence who can move value, when, and at what cost.
It also anticipates a modern argument: finance is not primarily about “money,” but about time and conversion. Petty’s phrasing compresses the whole sector into two levers that still govern everything from mortgages to currency crises, and in doing so, demystifies banking while warning you where its real power sits: in setting the terms.
Quote Details
| Topic | Money |
|---|---|
| Source | Help us find the source |
| Cite |
Citation Formats
APA Style (7th ed.)
Petty, William. (2026, January 18). The trade of banks is the buying and selling of interest and exchange. FixQuotes. https://fixquotes.com/quotes/the-trade-of-banks-is-the-buying-and-selling-of-8177/
Chicago Style
Petty, William. "The trade of banks is the buying and selling of interest and exchange." FixQuotes. January 18, 2026. https://fixquotes.com/quotes/the-trade-of-banks-is-the-buying-and-selling-of-8177/.
MLA Style (9th ed.)
"The trade of banks is the buying and selling of interest and exchange." FixQuotes, 18 Jan. 2026, https://fixquotes.com/quotes/the-trade-of-banks-is-the-buying-and-selling-of-8177/. Accessed 12 Feb. 2026.
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