Thérèse Humbert's fraud lasted twenty years and was built around a piece of furniture.
The story was that in 1879, aboard a train, she had nursed a sick American millionaire named Robert Henry Crawford, who had subsequently died and left her a fortune in bonds. The bonds were in a safe in her house on the Avenue de la Grande Armée in Paris. They could not be touched, because Crawford's nephews were contesting the will, and the safe was under seal pending litigation.
On the strength of the sealed safe she borrowed. Estimates run to sixty or a hundred million francs over two decades, from banks, insurance companies and private lenders. She and her husband — the son of a French justice minister — lived on an enormous scale, entertained politicians and financiers, and were among the most prominent figures in Paris society.
The safe was the whole architecture, and its power came from being permanently unopenable.
Karl Popper's criterion is the right way to see it. A claim that can be tested can be refuted; a claim insulated from testing accumulates belief through the absence of disconfirmation rather than the presence of evidence. Every year the safe went unopened was a year in which nothing contradicted the story, and lenders experienced the passage of time as reassurance.
The litigation was the second element and it is the cleverer one. Ongoing lawsuits about the inheritance meant that courts were engaged with the matter, and institutional engagement functions as a legitimacy ritual. A dispute being adjudicated is a dispute about something real. The Humberts kept the litigation alive deliberately, and at points appear to have funded both sides — the Crawford nephews were played by relatives.
Third, and most consequential: informational cascades. Bikhchandani, Hirshleifer and Welch's model describes how rational individuals, observing the actions of others who acted before them, can rationally ignore their own private information — and the result is a sequence in which nobody has performed the primary check and each person's participation is evidence to the next. Every lender to the Humberts knew that the largest banks in France had already lent, which was more persuasive than anything they could have discovered themselves.
It ended in May 1902, when a newspaper campaign forced the issue and a court ordered the safe opened. The Humberts fled the day before. The safe was opened in the presence of officials and journalists and contained a brick, an empty jewel box, and an Italian copper coin.
They were traced to Madrid, tried in 1903, and sentenced to five years' hard labor.
The structural lesson is the one worth carrying into modern finance. A claimed asset that cannot be inspected, for a reason that is itself part of the story, is not an asset with a complication. The inability to inspect is the product.