Before There Was Money, There Was Interest
Somewhere in the Pacific Ocean, there is a stone disc the size of a car wheel sitting on the seafloor. It sank during a storm centuries ago. And yet, according to the people of Yap Island, it still has an owner — the family whose ancestor lost it during transport. Everyone on the island knows this. The stone counts as wealth.
Milton Friedman, recounting this story, pointed out the remarkable parallel with what happened in 1930s New York. When France grew nervous about the US dollar and demanded to repatriate its gold holdings from the Federal Reserve, the gold never actually moved. A Fed official simply walked to the shelf marked "United States," changed the label to "Banque de France," and that was the end of it. France's gold was now in New York — and everyone agreed that was fine.
The same psychology, twelve thousand miles and three hundred years apart.
This parallel is the first thing that struck me reading Toshihiko Itaya's Sekai Kin'yushi (世界金融史：バブル、戦争、そして株式市場), a sprawling chronological survey of finance from Mesopotamian clay tablets to the 2008 crisis. Itaya wrote it as an accessible history for individual investors — not a polemic, not an ideological argument, just a careful account of how financial tools evolved and why. The book is modest in its ambitions. But read with an investor's eye, it becomes something stranger and more useful: a catalogue of the patterns we keep repeating, and a quiet argument for humility about everything we think we know.
I'm sharing my reading of it here as one investor's perspective, not as investment advice. Everything I write reflects my interpretation; nothing here should be mistaken for a recommendation about what to buy, sell, or hold.
Finance Is Older Than Money
The detail that most stopped me early in the book: interest existed before coins.
In ancient Mesopotamia, loans were recorded on clay tablets — grain lent against future grain, silver against future silver. The Code of Hammurabi, dated around 1750 BCE, didn't introduce interest. It capped it. Grain loans were limited to 33.3%; silver loans to 20%. The lower rate for silver reflects a real economic logic: grain was scarce at sowing time and abundant at harvest, so lending it commanded a premium. Silver held its value. The lender's risk differed, and the price differed accordingly.
The concept of "interest" itself, Itaya notes, came from livestock. When you lend a cow, you get back a cow — plus calves. The Chinese character for interest (利) combines grain with a knife: the yield cut from the field. Interest wasn't an invention of financiers. It emerged from the observation that living things reproduce.
Options trading is equally ancient. Around 600 BCE, the Greek philosopher Thales of Miletus paid deposits to monopolize the use of every olive press in his region. He had studied astronomy and believed the next harvest would be exceptional. When it was, he controlled the chokepoint and charged monopoly rates. In modern terms, he had purchased call options — the right to use the presses at a pre-agreed price. The olive press owners had sold covered calls. The farmers who bet against Thales without owning presses had sold naked calls with theoretically unlimited downside. The vocabulary is new. The mechanism is 2,600 years old.
What does this mean for investors today? Not much in a direct sense — I'm not about to trade grain futures on a theory derived from Mesopotamia. But it reframes something. Many things we treat as sophisticated modern inventions — derivatives, leverage, securitization — are actually ancient human impulses dressed in contemporary clothing. If options have been re-invented independently in ancient Greece and 17th-century Japan (more on this shortly), they're not clever financial engineering. They're something more fundamental about how humans manage uncertainty. That should make us more careful about arguments that "this time, we finally have the right model."
Japan Invented Futures in Isolation
One of the book's most striking chapters covers the Dojima Rice Exchange in Osaka.
By 1620, Japanese merchants were already trading rice options with precise parameters: a 12% premium (the option price), plus 3% interest, for the right to buy rice at the current market price — what we would today call an at-the-money call option. By 1730, the Tokugawa Shogunate officially sanctioned what it called "empty trading" (帳合米商い): rice futures that involved no physical delivery of rice at all, settling only the price difference in cash.
This was a country under sakoku — deliberate isolation from the outside world. Dutch traders were confined to a small island in Nagasaki harbor. Yet Japanese merchants, driven by the same pressures of price uncertainty that motivated every trader everywhere, independently arrived at cash-settled derivatives. The same mechanism, emerging from the same human needs, with no cross-pollination.
The Dojima exchange predated the formal cash-settled futures markets in the West by roughly 150 years.
I find this genuinely humbling. Financial innovation tends to be presented as linear progress, one country learning from another, institutions building on institutions. Dojima suggests something else: that certain financial structures are almost inevitable given sufficient commercial activity and price volatility. When the conditions are right, the instruments emerge. Which raises a question worth sitting with: what financial structures are emerging right now, driven by underlying human needs, that we haven't properly named yet?
The Anatomy of a Bubble
Itaya traces four major bubbles in detail — Dutch Tulip Mania (1630s), the Mississippi Company (1719-1720), the South Sea Bubble (1720), and Japan's asset bubble (1985-1990) — and the pattern is nearly identical each time.
The ingredients: a new asset class or financial instrument that makes it easy to buy with borrowed money; a period of genuine returns that draws in more participants; growing leverage as early winners borrow to buy more; a narrative that justifies why "this time" the fundamentals support the prices; and then, at some point, a crack in confidence that causes leveraged holders to sell, which lowers prices, which triggers margin calls, which causes more selling.
The Mississippi Company is perhaps the most instructive. John Law, a Scottish gambler turned French finance minister, engineered a system in which the French national debt was converted into shares in the Mississippi Company, which held a monopoly on French colonial trade. The company's stock rose from 550 livres in June 1719 to 10,000 livres by December — an 18-fold increase in six months. Law's system required continuous share price appreciation to function. When confidence cracked, the stock collapsed back to near zero within months, triggering the first paper-money hyperinflation in European history.
Law was a genuine intellectual, not simply a fraudster. His insight — that economic growth requires circulating money, and that scarce gold constrains the money supply — wasn't wrong in principle. But he built a structure that depended on the bubble continuing forever. When it didn't, everything unwound.
What I take from this pattern: bubbles rarely look like bubbles from the inside, because the early stages involve genuine value creation. The tulip bulb was a luxury good with real demand. Mississippi Company shares represented real colonial assets. Japan's real estate was backed by genuine economic growth and low interest rates. The fraud, such as it is, happens in the pricing — when the asset is valued not on its earnings but on the expectation that someone will pay more tomorrow.
One warning sign the book implicitly identifies: watch where the leverage is. Every major bubble has involved some mechanism that allowed investors to buy assets with borrowed money at low cost. Margin debt, repo markets, structured products with embedded leverage — the specific instrument changes, the underlying dynamic doesn't. When leverage is cheap and widespread, the correction, when it comes, will be violent precisely because deleveraging is procyclical. Everyone has to sell at once.
I don't know where the current leverage is. I have my suspicions, but I'm not going to pretend that reading history gives me the ability to time markets. The book's own conclusion is relevant here: "After reviewing the long financial history, what we can realize is perhaps only the point that 'the future is difficult to predict.'" Itaya says this without irony, and I believe him.
The Bell Curve Lies
The section of the book I've thought about most since finishing it covers the statistical foundations of modern portfolio theory — and its failure.
The argument runs as follows. Random Walk theory, as formalized by Eugene Fama in 1965 and popularized by Burton Malkiel's A Random Walk Down Wall Street (1973), models daily stock returns as a normal distribution — the bell curve. This is mathematically convenient and theoretically elegant. It also generates predictions that are demonstrably wrong.
Under a strict normal distribution, the -22.61% crash on Black Monday (October 19, 1987) has a probability of roughly 10^-80. That number is not just small. It is, as Itaya puts it, "absolutely impossible" — smaller than the probability of randomly assembling a human being from loose atoms. Except it happened.
Looking at 116 years of Dow Jones data — 29,850 trading days from 1896 to 2012 — daily drops of 5% or more occurred 97 times in reality. A perfect bell curve predicts 0.22 occurrences over the same period. The actual frequency was roughly 440 times higher than the model predicts.
The problem is well-known in academic finance — Nassim Taleb has written extensively about it, Mandelbrot identified it in the 1960s — but it persists in practice because the normal distribution is tractable. You can build optimizers around it. You can calculate Value at Risk. You can satisfy regulators. The alternatives are mathematically messier and commercially inconvenient.
For individual investors, the practical implication is simple: do not trust risk models that are built on historical volatility. When people say a portfolio has a "95% confidence interval" of a certain range of returns, that confidence interval is calculated using a distribution that has been empirically wrong about tail events for over a century. The tails are fat. The catastrophes are more frequent than the models imply. Plan for them.
This doesn't mean holding cash forever, which carries its own costs. It means: don't use leverage that would force you to sell in a crash. Don't put yourself in a position where a -30% drawdown triggers margin calls. The market will recover. But as Itaya shows in the next section, "recovery" is a word that deserves more scrutiny than it usually receives.
The "Long Run" Is Longer Than You Live
The standard argument for equity investing runs like this: over long periods, stocks beat everything. Even after crashes, they recover. The 1929 crash? The Dow Jones recovered by the early 1950s, and has gone on to all-time highs since. Patient investors are rewarded.
Itaya adds one adjustment that changes the picture considerably: inflation.
The nominal Dow Jones recovered its 1929 peak around 1954 — roughly 25 years. But the real Dow Jones, adjusted for consumer price inflation, didn't recover until the late 1980s. Nearly 60 years.
A 25-year-old investor in 1929 would have been 84 before their real wealth returned to where it started. They would, in all likelihood, have never recovered.
The 1970s tell a similar story. The S&P 500's nominal value moved roughly sideways through the decade; people remember it as a flat market. But the real, inflation-adjusted S&P 500 fell by 62.5% between 1968 and 1982. The portfolio that looked stable in nominal terms was quietly being eaten.
I find this genuinely sobering, not because it argues against equity investing — I still hold index funds as the core of my portfolio — but because it forces precision about what "long term" means. "Stocks recover over the long run" is technically true, but "the long run" can exceed a human lifespan or working career. The relevant question for any individual investor is not "will markets eventually recover?" but "will markets recover within my investment horizon, given my age, my obligations, and my need for real (inflation-adjusted) purchasing power?"
These are not questions that financial history can answer for you. They're questions only you can answer for yourself.
What History Can and Cannot Do
I want to be honest about the limits of this kind of reading.
Itaya himself is explicit about it. The book ends not with confident prescriptions but with the admission that what financial history teaches us, above all, is that prediction is hard. Every generation produces people who study the past and believe they can forecast the future from it. Most of them are wrong most of the time.
The value of reading financial history, as I experience it, is not predictive but calibrative. It changes what I treat as normal. A world without financial crises is the aberration, not the default — crises have happened in every century for which we have records, in every financial system, in every ideology. A world in which the most sophisticated risk models fail catastrophically is not a broken world; it is the world as it actually operates.
More usefully: history makes certain patterns recognizable. Cheap leverage flowing into a new asset class, accompanied by a compelling narrative about why prices are justified — this I now notice when I see it, not because I know what will happen, but because I know what has happened before. I treat it as a reason to ask harder questions, not as a signal to buy or sell.
The three things I've actually changed in how I think about investing since reading Itaya's book:
First, I now insist on inflation-adjusting every historical comparison. Nominal numbers lie.
Second, I treat risk model outputs as lower bounds on tail risk, not accurate estimates. Whatever VaR or standard deviation says, reality is fatter-tailed.
Third, I think about leverage anywhere in the system, not just in my own portfolio. When aggregate margin debt rises sharply, the entire market becomes more fragile — not because of anything I'm doing, but because my fellow investors have collectively borrowed against their positions, and their forced selling will affect my holdings regardless.
None of this is investment advice. I am one investor, sharing a reading of one book, in a moment of genuine uncertainty about where markets go from here. The history suggests that uncertainty is the permanent condition, not a temporary interruption. Working with that, rather than against it, seems like the most durable framework I've found.
This post reflects my personal reading of Toshihiko Itaya's 世界金融史 (2016). Nothing here constitutes financial advice. I hold equity index funds and make no claims about the direction of any market.
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