The global financial crisis started in 2007 when European banks came under increasing strain. If forced to specify the crisis kickoff, we would pick Thursday, August 9, the day that BNP Paribas halted redemptions from three investment funds because it couldn’t value their holdings of U.S. mortgages. Responding to the ensuing market scramble for liquidity, the ECB injected €95 billion that day into the European banking system and the Federal Reserve put $24 billion in theirs. Today, with the benefit of hindsight, these numbers appear quaint, but then they seemed enormous...