For that rule of thumb is largely composed of observations of what has happened in past supply shocks.

FORBES: Peak or Plateau Oil, Oil Prices and Economic Growth

But if Milton Friedman and Anna Schwartz were right in their insistence that it was actually the Federal Reserve that caused the Great Depression (which is something that Ben Bernanke himself has insisted that the Fed will not repeat) then one way of interpreting what has happened is that the European Central Bank has just set us all up for another Depression.

FORBES: Cyprus Bailout: Welcome To Another Great Depression

"We can confirm that a staff member is not accounted for and we are in touch with the relevant parties to determine what has happened, " UN spokesman Eduardo del Buey told the Associated Press.

BBC: Syrian rebel fighters (30 January 2013)

"For me the war is still present - it's present in all the families that do not know the truth about what has happened, " says Father Cortina, who spent much of the war as a parish priest in one of the most conflict-ridden areas of the country.

BBC: The BBC's Mike Lanchin