Investors called on the Bank of Japan, which three weeks ago reduced a peripheral interest rate, to cut the main rate, raised from 0% to 0.5% in August on hopes of a recovery in the country's economy.

BBC: Japan stocks hit 15-year low

Now, in the doldrums, those peripheral countries need negative interest rates (not possible as such, but there are monetary means of getting to a similar result).

FORBES: The Inevitable Failure of the Euro

Nor will devolution remain of interest only to the peripheral nations.

ECONOMIST: Britain

As European peripheral countries have found out to their cost, interest rates increase when governments run large budget deficits, and as they do it becomes increasingly difficult to reduce r-g to a sustainable level.

ECONOMIST: Daily chart

And as you can see the desired, target, interest rates are very different for the peripheral countries (Portugal, Ireland, Greece, Spain, the so called PIGS) than they are for the core countries (Belgium Holland, Germany, France etc).

FORBES: The Inevitable Failure of the Euro

Which means that those peripheral economies are condemned to a cycle of huge boom and bust as interest rates are either way too low or way too high for their circumstances.

FORBES: The Inevitable Failure of the Euro