There are places in and around our great cities, where the natural world has all but disappeared. You can make out streets and sidewalks, autos, parking garages, advertising billboards, monuments of glass and steel. But not a tree, or a blade of grass or any animal, besides of course, the Humans. There are lot’s of Humans. Only when you look up straight up through the skyscraper canyons, can you make out a star or a patch of blue. Reminders of what was there long before humans came to be. It’s not hard going to work every day in such a place to be impressed with ourselves. How we’ve transformed the earth for our benefit and convenience. But a few hundred miles up or down, there are no humans, our impact on the universe is nil. In the last 10,000 years, an instant in our long history, we’ve abandoned the nomadic life. We’ve domesticated the plants and animals. Why chase the food, when you can make it come to you? For all its material advantages, the sedentary life has left us edgy, unfulfilled. Even after 400 generations in villages and cities, we haven’t forgotten. There are now people on every continent and the remotest islands. From pole to pole. From Mount Everest to the Dead Sea. On the ocean bottoms, and even, occasionally in residence two miles up. Humans, like the Gods of old, living in the sky. These days there seems no where left to explore. Victims of their very success, the explorers now, pretty much, stay home.