For the past few months, the media has been watching the Dow Jones Industrial Average the way a hypochondriac checks his thermometer. And the higher the Dow's temperature goes, the more we need to sweat.

The Dow's autumnal visit to 10,000 is opposite in mood and cause to the springlike euphoria that marked the same milestone in March 1999. Part of the reason we can't rejoice is that we are now cursed with self-awareness. The tech bubble broke our hearts, and the mortgage bubble broke our spirits. As Eric Jackson, the founder of hedge fund Ironfire Capital, says: We’ve lost our innocence. “My apprehension is more like living in a post-9/11 world," he explains. "I'm more skeptical, vigilant, fearful."