Sometimes vanity is a good thing. Just ask my friend Angela. One day some years back she was riding the subway to work. She was really excited that morning because she was going to be interviewing for a big promotion in another department. Her boss thought she was a lock for the promotion, but even so, she had been up at the crack of dawn to make sure that her clothes, her makeup, and her hair were just right.

But everything else seemed to be going wrong. She had missed her usual train, which meant that she would have to rush through the mall under her building and then fight for space on an elevator. The probability of her arriving on time was practically nil.

And then things got even worse. When she finally arrived at the station, there seemed to be some kind of problem. The air outside the train was thick with what looked like smoke or dust, not a good thing for her clothes or her hair.

So, interview or not, she decided that being late would be preferable to showing up with bad hair and dusty clothes. So she stayed on the train, deciding to take it one more stop and then walk back to her building.

When she emerged from the next station, the world had changed. It was September 11, 2001.