It has been three decades since Business Week proclaimed “The Death of Equities” on its cover. That 1979 obituary for the stock market, published when the Dow Jones industrial average languished at a mere 875, became a symbol of an age of doubt. So shattered were ordinary Americans by gas lines, recessions and double-digit inflation that they resorted to pulling cash out of equity mutual funds — for eight straight years.

Investors in the ’70s were stunned by an alarming rise in volatility. The comfortable, ordered system of international exchange, in place since the Bretton Woods accord at the end of World War II, had come apart, leading to violent fluctuations in currency values. Grain shortages sent food prices soaring, and memorably, OPEC put...