In the spring of 1720 Isaac Newton stated: ‘I can calculate the motions of the heavenly bodies, but not the madness of people.’ On April 20, accordingly, he sold his shares in the South Sea Company at a 100 percent profit of £7000.  Later an infection from the mania gripping the world that spring and summer caused him to buy a larger number of shares near the market top and he lost £20,000. In the irrational habit of so many who experience financial disaster, he put it out of his mind and never for the rest of his life could he bear to hear the name South Sea.
– Manias, Panics, and Crashes