From 1929 to 1932 the main government in the firing line - America - operated a pro-cyclical policy of deflation: that is, making the downturn worse in the belief that it would "cleanse the system".
Banishing Japan's persistent state of mild deflation has been a key policy pledge of prime minister Shinzo Abe, whose conservative Liberal Democratic Party returned to power last month after three years in opposition.
If driving rates down to zero was, above all, a measure to combat deflation, the policy should be abandoned only when the threat of deflation is lifted.
Expectations that Mr. Abe's Liberal Democratic Party, which came to power in December, would implement an aggressive monetary policy to end 15 years of deflation sent the currency tumbling.
The lesson from Japan is that, if there is the slightest risk of deflation, monetary policy needs to be looser than warranted by current economic conditions.
The instrument is implemented in the UK and US, where the central banks consider that there are risks of deflation and where the policy rate is constrained by the zero lower bound.
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The second and no doubt leading contributor to the gold bubble has been the world financial crisis of 2008-2009 and the subsequent worldwide central bank policy of monetary expansion to fight financial asset price deflation.
Most serious of all, deflation can make monetary policy ineffective: nominal interest rates cannot be negative, so real rates can get stuck too high.
Another gold member, James Dines, editor of the Dines Letter, says that the Fed's fear of deflation has prompted a highly stimulative monetary policy.
Japan's gold-selling boom could soon turn to gold-buying, analysts say, if policy makers succeed in their goal of ending 15 years of deflation and sparking a new round of inflation.
The Bank of Japan allowed deflation to develop when it held policy too tight, partly because it was worried about another asset-price bubble.
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With Bernanke and Co. pledging to keep buying bonds until the end of June and also to maintain ZIRP (zero interest rate policy) for as long as there is any threat at all of deflation, traders knew exactly what to do.
Deflation has been one of the biggest bugbears for Japanese policy makers as it holds back consumer spending.
But Japan must also act "to finally break free of the deflation trap" and it needed to "rely more on monetary policy to kick-start growth".
The first signs of deflation could lead to a harsh sell-off in gold, but policy makers, particularly in the United States, are keen to avoid such a scenario.
The yen's slump across a range of currencies has occurred as a new government has pledged to revive the deflation-dogged Japanese economy and has pressured the Bank of Japan to aggressively ease monetary policy.
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