Issue No. 312 · The Weekly Foundation
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From a recent issue · No. 309
On compounding, explained without the usual graph
The trouble with most explanations of compound interest is that they reach for the hockey-stick chart almost immediately — a slow curve, then a sharp upward turn, then a shrug and a tagline about "the magic of time." The chart is correct, but it is also lazy. It hides the only thing worth saying: that compounding is not a property of money, it is a property of any quantity that feeds a fraction of itself back into itself. Populations do it. Rumours do it. Errors in a measurement do it. The interest rate in your savings account is just one dial on a much older machine.
Once you see the machine, the chart stops being magical and starts being readable. You begin to ask the only useful question — what is the feedback fraction, and what is it feeding on? — instead of wondering when, exactly, the curve will turn.
— From "The feedback machine," The Weekly Foundation, Issue No. 309, October 2025.
Recent issues
Twelve years of Sundays, indexed.
A small selection from the last six weeks of publication. The full archive — every issue since the first, in March 2014 — is open to readers and searchable by subject.
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No. 312 Sun, 11 Jan 2026
Biology
What a cell actually is, before it became a textbook diagram
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No. 311 Sun, 04 Jan 2026
Economics
The unit of account, and why price is a story rather than a number
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No. 310 Sun, 28 Dec 2025
Computing
A loop, a counter, and the entire history of programs in two lines
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No. 309 Sun, 21 Dec 2025
Mathematics
The feedback machine — compounding without the hockey stick
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No. 308 Sun, 14 Dec 2025
Psychology
Attention is a budget, not a bucket — and the ledger is older than you think
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No. 307 Sun, 07 Dec 2025
History
The printing press as a logistics problem before it was an information one
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