Today is my eightieth birthday and I'm beginning to feel old.

I didn't feel old when I turned seventy. I had a full-time job, I was biking long distances on summer vacations, and I only took one pill in the morning. Now, ten years later, I'm retired, I take about ten pills a day, and seldom bike more than two miles

Don't get me wrong. I'm still happy to be on this side of the grass. I'm happy to wake up next to Judy in the morning. I'm happy to learn something new almost every day. I'm happy when I hear Mozart or come up with a new idea. And I still like managing the things I run.

So far so good. But I wonder how I'll feel when I turn ninety…if I turn ninety.

I'd like to turn ninety, and keep going, because there are still lots of things I'd like to do. I want to see what happens to my children and grandchildren. I have things I'd like to teach, some research problems I'd like to solve and a martini or two I'd like to drink..

Although ordinarily I don't like being interrupted while I'm in the middle of doing something, that's how I'd like to go – while I'm in the middle of doing something. But, as Saint Augustine said after he asked his God for chastity, not yet.