Remember the crash of 1907? Probably not. Everyone talks about the Crash of 1929, but no one talks about the Crashes of 1937, or 1907, or 1873, or 1857 … or others. And why not? Because we like our lessons familiar and simple. And the lesson of the Crash of 1929, in simplified form, was that the Roaring ’20s had fostered a time of excess wealth and market speculation–much of it on margin; and that as buying dried up and sellers took control, the domino effect brought a big long crash, the eventual evaporation of billions of dollars in...