Author Freeman Tilden observed that when the Greek philosophers examined the world about them they concluded that the elements of earth, air, fire and water were the fundamental building blocks of all that they observed. Still, he said, they believed that there must be something else, something intangible. If they could find it, there was a soul of things, a fifth essence, pure, eternal and inclusive. I have discovered it in places like Yellowstone, Glacier, Sequoia and Everglades, and it has enriched my life with understanding and meaning.