Coming back to your native land after an absence of many years is a surprisingly unsettling business, a little like waking from a long coma. Time, you discover, has wrought changes that leave you feeling mildly foolish and out of touch.

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

If a potato can produce vitamin C, why can't we? Within the animal kingdom only humans and guinea pigs are unable to synthesize vitamin C in their own bodies. Why us and guinea pigs? No point asking. Nobody knows.

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.

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

Where I grew up, in Des Moines, Iowa, there is hardly any downtown economic activity now. Everybody shops in malls - you don't find a sense of community in malls.

Protons give an atom its identity, electrons its personality.