And as the great American economist Irving Fisher pointed out in the 1930s, the things people and companies do when they realize they have too much debt tend to be self-defeating when everyone tries to do them at the same time. Attempts to sell assets and pay off debt deepen the plunge in asset prices, further reducing net worth. Attempts to save more translate into a collapse of consumer demand, deepening the economic slump.

Are policy makers ready to do what it takes to break this vicious circle? In principle, yes. Government officials understand the issue: we need to “contain what is a very damaging and potentially deflationary spiral,” says Lawrence Summers, a top Obama economic adviser.

In practice, however, the policies currently on offer don’t look adequate to the challenge. The fiscal stimulus plan, while it will certainly help, probably won’t do more than mitigate the economic side effects of debt deflation. And the much-awaited announcement of the bank rescue plan left everyone confused rather than reassured.

There’s hope that the bank rescue will eventually turn into something stronger. It has been interesting to watch the idea of temporary bank nationalization move from the fringe to mainstream acceptance, with even Republicans like Senator Lindsey Graham conceding that it may be necessary. But even if we eventually do what’s needed on the bank front, that will solve only part of the problem.

If you want to see what it really takes to boot the economy out of a debt trap, look at the large public works program, otherwise known as World War II, that ended the Great Depression. The war didn’t just lead to full employment. It also led to rapidly rising incomes and substantial inflation, all with virtually no borrowing by the private sector. By 1945 the government’s debt had soared, but the ratio of private-sector debt to G.D.P. was only half what it had been in 1940. And this low level of private debt helped set the stage for the great postwar boom.

Since nothing like that is on the table, or seems likely to get on the table any time soon, it will take years for families and firms to work off the debt they ran up so blithely. The odds are that the legacy of our time of illusion  our decade at Bernie’s  will be a long, painful slump.