All those who forget are doomed to be reminded

1. Without bear markets to take stock prices back down, anyone waiting to "buy low" will feel completely left behind - and, all too often, will end up abandoning any former caution and jumping in with both feet.
2. That's why Graham's message about the importance of emotional discipline is so important.
3. From October 1990 through January 2000, the Dow Jones Industrial Average marched relentlessly upward, never losing more than 20% and suffering a loss of 10% or more only three times. The total gain (not counting dividends): 395.7%.
4. According to Crandall, Pierce & Co., this was the second-longest uninterrupted bull market of the past century; only the 1949-1961 boom lasted longer.
5. The longer a bull market lasts, the more severely investors will be afflicted with amnesia; after five years or so, many people no longer believe that bear markets are even possible.
6. All those who forget are doomed to be reminded; and, in the stock market, recovered memories are always unpleasant.
   
   

Ref: Intelligent Investor by Benjamin Graham