As I walked across the mottled clay tiles of the Alvord Desert, I was struck by the impermanence of everything.  Thousands of years ago, the ground beneath me was submerged in two hundred feet of water.  Geological change caused the then-lake to burst forth from its confines and fill rivers to the south.  Today, the 140 square mile "playa" is dry half the year.  During the season of my visit - when most of the five inches of average annual precipitation falls on the desert - water crept across the landscape like a mirage from the northeast.  I stood alongside it and watched as it bubbled closer and closer to my feet.  Slowly.  Surely. In the words of the Buddha, Everything vanishes.