The national treasuries all ran out of money trying to stop the plunge, and weakened economies followed.
And after the stock market went into free fall in October 1929, neither predicted that the economy would soon follow.
Instead of leading the market, the real economy now follows it.
The human economy follows the same natural laws.
But it is not clear that the world or the economy will follow the same script this time.
That assumes, of course, that the economy will follow the same regularities as over the last four decades.
This emphasises the consistent features of 300 years in which the economy followed a stop-go path.
It is remarkable that two major economies have followed such very different paths to get to such similar problems.
Most other advanced and emerging economies followed, chiefly in the 1980s and early 1990s.
Even with the aid, the country's economy has followed a haphazard course.