Among the painful signs of our time are the shocked reactions to Chuck Norris' raising the question of whether Senator John McCain is too old to be president.

Have we reached the point where we have so many politically correct taboos that we can't even talk sense?

Does a man in his seventies have less energy for either physical or mental tasks than someone younger? Those of us who are in our seventies know darn well that we can't do everything we used to do, as well as we used to do it.

It was appalling to me when my driver's license was renewed last year without my having to get behind the wheel of a car and demonstrate that I still could drive safely.

Even if my own driving was still all right, I could get killed by some other old-timer whose driving was not all right -- and who had not been tested behind the wheel for many years.

While teenagers have high rates of fatal accidents, the decline that sets in as they mature does not continue indefinitely. The rate of fatal accidents declines to a plateau in middle age -- and then begins to rise again for older people, until old-timers eventually reach the point where their rate of fatal accidents is at least as high as that of teenagers.

It is not just in physical tasks that age takes its toll. Even when our minds remain sharp, our energy levels are seldom the same, and that affects how long we can concentrate on a given day without taking a rest.

It is easy enough for me to take an afternoon nap and wake up refreshed, especially since my younger research assistants are working while I am dozing, and have plenty of material ready for me when I am ready to resume work.

But a President of the United States has to be ready to take on any crisis that arises anywhere in the world, at any hour of the day or night.

And if he has to deal with it around the clock, then he just stays awake around the clock to deal with it.

It can be a killing job. You need only look at pictures of Abraham Lincoln when he took office and compare them with the pictures of him just a few years later, when he looked like he had aged at least ten years during the Civil War.

Look at pictures of Franklin D. Roosevelt taken in 1940 and compare them with pictures of him taken in 1945, after World War II had taken its toll.

Today we know that FDR's doctor had put him on a restricted schedule -- and that still was not enough to keep him from dying in office, just a few months after he began his final term as President. Continued...