Look at the tale of two housing markets on either side of the Atlantic. The way they evolve in the coming months could well dictate our wider prosperity.
Both have a recent history of an explosive re-rating of house prices at a time of otherwise dormant inflation - so explosive that by any historical comparison they were bubbles heading for a burst.
By hindsight they can equally plausibly be seen as one-off adjustments to the low interest rates that came with low inflation.
Fears that something nasty could happen came first in Britain. Instead, to the surprise and relief of some of us, we had the blessed "soft landing". The housing market stalled in August, 2004, did nothing much for a few months, then crept quietly back to life, yet without alarming price increases.
The pace quickened stead-ily after the Bank of England trimmed interest rates last August. Then yesterday the Bank reported a sharp and unexplained dip in February in the number of mortgages approved for house purchase.
It so happened this coincided with a round of bumper City bonuses - so bumper that it turns out that the taxes on them saved Gordon Brown from having to revisit the Budget arithmetic he announced last December.
Those bonuses, along with handsome stock market prof-its, duly fuelled a bout of house buying and some giddy prices mostly confined to the West End of London. There are now signs of this already rippling out into some suburbs. Estate agents are again writing to householders urging them to put their homes up for sale to take advantage of "the hottest market we have seen for five years".
In past booms, ripples like this have spread across the country over two or three years. One difference this time, to judge by the Bank's numbers, is that it is being funded more by cash than by another round of headlong mortgage borrowing. That may mean it fizzles out once the cash is spent. Or it may not. People who sell their homes for an enormous profit have cash, too. It depends on how many of them put it back into bricks and mortar and drive prices up somewhere else.
The other difference is that, if we are getting into another round of fast-rising house prices, it is starting from a high base, fragile because already beyond the reach of many would-be first-timers. Plainly, the risk that it ends badly is greater than it was two years ago.
As to America, remortgages backed by their house price explosion have kept a consumer boom bubbling through 15 interest rate increases on 20 months, the last of them this Tuesday, accompanied by a strong hint of more to come. The Fed, which sets the rate, has a new chairman, Ben Bernanke, who needs to prove he is not soft on inflation.
We shall see whether he manages that without pulling the rug from under the US housing market. If he gets it wrong, he could remove the main driving force behind the entire American economy.
Note: sales of new homes in the States fell sharply in February, before Mr Bernanke did anything. ..SUPL: