A small, grubby, windowless room up a flight of stairs in central Shanghai demonstrated the reach and limits of financial globalisation.
The walls were studded with old-fashioned, cathode-ray screens showing share prices of Chinese companies.
And the dank airless space was mobbed with men and women in later middle age, most of them retired, who were speculating frantically.
This was the electronic market in its least sanitised form.
Greed, fear, hope, despair - they were all on display as ladies with dyed hair of an indeterminate colour whooped and shrieked over the ups and downs of their nest eggs.
The basic requirement for trading here is savings of at least £10,000 - though some have ten times that. Even so, these are not flashy, well-groomed speculators.
In their jumpers and slacks, they'd look more at home in a bus shelter than on a trading floor.
Although Chinese shares have lost 60% of their value over the past year and a bit, in recent weeks the trend has been sharply up.
How has China bucked the falls in share prices that have infected most stock markets since the start of the year?
Part of the explanation, according to economists, is the £250bn surge in lending by the state-controlled banks in December and January - because some of these loans have been used to buy shares.
Does this represent an explicit state-sponsored operation to support the stock market?
Like so much of what happens here in a form of capitalism whose tooth-and-claw redness is the colour of the Communist Party, it's hard to be sure.
If this is two fingers in the face of global market declines, it'll probably only work for a while: as I mentioned yesterday, the outlook for many Chinese companies, especially exporters, isn't great.
So the thought I couldn't shake off when watching the oldies' stock-market enthusiasm is that this was an addiction.
And it was probably the nearest I will ever witness to the market mania of ordinary Americans crowded round ticker tapes in the 1920s - before the Great Crash and Great Depression.
Which is not to overstate the similarities between America of 80 years ago and China today.
Because - just like Britain, America and much of the developed world - China is trying to refuel its economy with a potent mixture of public spending, cheap money and new bank loans for businesses.
In one respect, China has a significant advantage over the rich West: its banks are strong and well-capitalised, with significant capacity to provide the credit that's vital to an economic recovery.
But bank loans are useless for companies when demand for their products and services has collapsed.
To state the obvious, lending to businesses that aren't viable is throwing good money after bad.
And propping up the share prices of companies that are under pressure by buying their shares with borrowed money would probably be worse.