Under most conditions, the best roof for your bedroom is the sky. This commonsense arrangement saves weight, time, energy, and money.

God is light, we are told, and Hell is outer darkness. But look at a desert mountain stripped bare by the sun, and you learn only geography. Watch darkness claim it, and for a moment you may grasp why God had to create Satan—or man to create both.

Mostly, two miles an hour is good going.

Even in these mercifully emancipated decades, many people still seem quite seriously alarmed at the prospect of sleeping away from officially consecrated campsites, with no more equipment than they can carry on their backs. When pressed, they babble about snakes or bears or even, by God, bandits. But the real barrier, I'm sure, is the unknown.

Frankly, I fail to see how going for a six-month, thousand-mile walk through deserts and mountains can be judged less real than spending six months working eight hours a day, five days a week, in order to earn enough money to be able to come back to a comfortable home in the evening and sit in front of a TV screen and watch the two-dimensional image of some guy talking about a book he has written on a six-month, thousand-mile walk through deserts and mountains.

I find that the three truly great times for thinking thoughts are when I am standing in the shower, sitting on the john, or walking. And the greatest of these, by far, is walking.

I had better admit right away that walking can in the end become an addiction ... even in this final stage it remains a delectable madness, very good for sanity, and I recommend it with passion.