Beside me was a tree, one lone tree. That tree was locally famous because it was the only tree anywhere in that vicinity; yet its presence proved that once there had been a forest over most of that land-now treeless and waste. The farmers of a past generation had cleared the forest. They had plowed the sloping land and dotted it with hamlets. Many workers had been busy with flocks and teams, going to and fro among the shocks of grain. Year by year the rain has washed away the loosened soil. The hamlets in my valley below the Great Wall are shriveled or gone. Only gullies remain -a wide and...