The basic prescription for preventing deflation is therefore straightforward, at least in principle: Use monetary and fiscal policy as needed to support aggregate spending, in a manner as nearly consistent as possible with full utilization of economic resources and low and stable inflation. In other words, the best way to get out of trouble is not to get into it in the first place.
Ben BernankeImportantly, in the 1930s, in the Great Depression, the Federal Reserve, despite its mandate, was quite passive and, as a result, financial crisis became very severe, lasted essentially from 1929 to 1933.
Ben Bernanke