When the economic history of the 21st century is written, September 2012 is likely to be recorded as a defining moment, almost as important as September 2008. This month’s historic events – Ben Bernanke’s promise to buy bonds without limit until the U.S. returns to something approaching full employment, Angela Merkel’s support for the European Central Bank bond purchase plans and the Bank of Japan’s decision to accelerate greatly its easing program – may not seem earth-shattering in the same way as the near-collapse of every major bank in the U. S. and Europe. Yet the upheavals now happening in central banking represent a tectonic shift that could transform the economic landscape as dramatically as the financial earthquake four years ago.