From Paul Krugman’s Partying Like It’s 1929: “Contrary to popular belief, the stock market crash of 1929 wasn’t the defining moment of the Great Depression. What turned an ordinary recession into a civilization-threatening slump was the wave of bank runs that swept across America in 1930 and 1931. This banking crisis of the 1930s showed that unregulated, unsupervised financial markets can all too easily suffer catastrophic failure. As the decades passed, however, that lesson was forgotten — and now we’re relearning it, the hard way.”