Almost six years since the global financial crisis reached its height, it's easy to forget just how close to the brink the world economy came. To someone like Reserve Bank governor Glenn Stevens, however, those events are burnt on his brain.
Which explains why he thought them worth recalling in a speech this week. And also why, so many years later, the major developed economies of the North Atlantic are showing little sign of returning to normal growth any time soon.
When those key decision-makers who lived through 2008 and 2009 say that there was the potential for an outcome every bit as disastrous as the Great Depression of the 1930s, ''I don't think that is an exaggeration,'' he says.
''Any account of the events of September and October 2008 reminds one of what an extraordinary couple of months they were. Virtually every day would bring news of major financial institutions in distress, markets gyrating wildly or closing altogether, rapid international spillovers and public interventions on an unprecedented scale in an attempt to stabilise the situation.
''It was a global panic. The accounts of some of the key decision-makers that have been published give even more sense of how desperately close to the edge they thought the system came and how difficult the task was of stopping it going over.''
But, despite the inevitable ''mistakes and misjudgments'', the authorities did stop it going over. Stevens attributes this to their having learnt the lessons of the monumental mistakes and misjudgments that that turned the Great (sharemarket) Crash of 1929 into the Great Depression.
Economic historians (including one Ben Bernanke) spent decades studying the Depression and, in Stevens' summation, they came up with five key lessons: be prepared to add liquidity - if necessary, a lot of it - to financial systems that are under stress; don't let bank failures and a massive credit crunch reinforce a contraction in economic activity that is already occurring - try to break that feedback loop; be prepared to use macro-economic policy aggressively.
So far as possible, maintain dialogue and co-operation between countries and keep markets open, meaning don't resort to trade protectionism or ''beggar-thy-neighbour'' exchange rate policies. And act in ways that promote confidence - have a plan.
There was a lot of action and a lot of international co-operation, and it worked. As a result, we talk about the Great Recession, not the Great Depression Mark II.
''We may not like the politics or the optics of it all - all the 'bailouts', the sense that some people who behaved irresponsibly got away with it, the recriminations, the second-guessing after the event and so on,'' he says. ''But the alternative was worse.''
With collapse averted, the next step was to fix the broken banks. Their bad debts had to be written off and their share capital replenished, either by them raising capital from the markets or accepting it from the government.
Fixing the banks' balance sheets was necessary for recovery, but not sufficient. A sound financial system isn't the initiating force for growth, so stimulatory macro-economic policies were needed to get things moving.
On top of the government spending to recapitalise the banks came a huge amount of fiscal (budgetary) stimulus spending. Stevens says a financial crisis and a deep recession can easily add 20 or 30 percentage points to the ratio of public debt to GDP.
Then you've got the weak economic growth leading to far weaker than normal levels of tax collections. Add to all that the various North Atlantic economies that had been running annual budget deficits for years before the crisis happened. ''So fiscal policy has not had as much scope to continue supporting recovery as might have been hoped,'' Stevens says. ''Policymakers in some instances have felt they had little choice but to move into consolidation mode [spending cuts and tax increases] early in the recovery.''
He doesn't say, but I will: this crazy, counterproductive policy of ''austerity'' has helped to prolong the agony.
With fiscal policy judged to have used up its scope for stimulus, that leaves monetary policy. Central banks cut short-term interest rates hard, but were prevented from doing more because they soon hit the ''zero lower bound'' (you can't go lower than 0 per cent).
But long-term interest rates were still well above zero and, in the US and the euro area, long-term rates play a more central role in the economy than they do in Oz. Hence the resort to ''quantitative easing''.
Under QE, the central bank buys long-term government bonds or even private bonds and pays for them merely by crediting the accounts of the banks it bought from. Adding to the demand for bonds forces their price up and yield (interest rate) down. And reducing long-term rates is intended to stimulate borrowing and spending.
Has it worked? It's intended to encourage risk-taking, but are these risks taken by genuine entrepreneurs producing in the real economy, or are they financial risk-taking through such devices as increased leverage?
Stevens' judgment is that it takes time for an economy to heal after a financial crisis so it's too soon to draw strong conclusions.
For Stevens, the lesson is that there are limits to how much monetary policy can do to get economies back to healthy growth after financial crises.
''If people simply don't wish to take on new business risks, monetary policy can't make them,'' he says.
Perhaps the answer is simply subdued ''animal spirits'' - low levels of confidence, he thinks. But, at some stage, sharemarket analysts and the investor community will ask fewer questions about risk reduction and more about the company's growth strategy.
