Consider the Lichen. Lichens are just about the hardiest visible organisms on Earth, but the least ambitious.

Open your refrigerator door, and you summon forth more light than the total amount enjoyed by most households in the 18th century. The world at night, for much of history, was a very dark place, indeed.

I love the feeling of being anonymous in a city I've never been before.

Every twenty minutes on the Appalachian Trail, Katz and I walked farther than the average American walks in a week. For 93 percent of all trips outside the home, for whatever distance or whatever purpose, Americans now get in a car. On average the total walking of an American these days - that's walking of all types: from car to office, from office to car, around the supermarket and shopping malls - adds up to 1.4 miles a week, barely 350 yards a day.

A cough so robust that I tapped into two new seams of phlegm.

There is the odd exception, like Albert Einstein, but as a breed, scientists tend not be very good at presenting themselves.

At the foot of the mountain, the park ended and suddenly all was squalor again. I was once more struck by this strange compartmentalization that goes on in America -- a belief that no commercial activities must be allowed inside the park, but permitting unrestrained development outside, even though the landscape there may be just as outstanding. America has never quite grasped that you can live in a place without making it ugly, that beauty doesn't have to be confined behind fences, as if a national park were a sort of zoo for nature.