“Do you do magic tricks?”

It is the villagers. They watch us pass under the blinding white sun of the Thar Desert. We are walking across India with a cargo donkey. Local people mistake us for vagabond performers, traveling quacks, circus nomads. The answer to their question of course is: yes. We carry magic. But so does everyone.

It lies in water.

Human beings are mobile wells of mildly salty water. As every schoolchild knows, our bodies contain the same fraction of water—71 percent—as the portion of the Earth’s surface that is covered by oceans. This is no mystery. We are water animals born into a water planet. Water is everywhere and nowhere. It is a restless compound—transitional, unstill, always on the move.