Fed Chair Ben Bernanke on Tuesday offered his perspective on the appropriate response of the Fed to the ongoing turmoil in financial markets. I still think he's overlooking a key element of what's been happening.Bernanke observed:Meeting creditors' demands for payment requires holding liquidity-- cash, essentially, or close equivalents. But neither individual institutions, nor the private sector as a whole, can maintain enough cash on hand to meet a demand for liquidation of all, or even...