There's a Chinese saying. 'When is the best time to plant a tree? Twenty years ago.' "The Chinese engineer smiles. "Good one."" 'When is the next best time? Now.' ""Ah! Okay!" The smile turns real. Until today, he has never planted anything. But Now, that next best of times, is long, and rewrites everything.

The boy thinks: Something slow and purposeful wants to turn every human building into soil.

Civilized yards are all alike. Every wild yard is wild in its own way.

No one sees trees. We see fruit, we see nuts, we see wood, we see shade. We see ornaments or pretty fall foliage. Obstacles blocking the road or wrecking the ski slope. Dark, threatening places that must be cleared. We see branches about to crush our roof. We see a cash crop. But trees - trees are invisible.