I asked one of our daughters, age thirty-five, how she feels about aging. "I don't have time to consider it," she answered, then paused. "I panic sometimes - about my biological clock." I asked a friend, age forty-nine, how she feels about aging. She replied, "When I used to forget things, it was funny. I was just 'ditsy.' My family, my friends and I, we all took it in stride. Now it's scary. I ask myself with every slip, "Is this...