When I drink from a glass or bottle, I think about the ubiquity of water. Aside from air, it is the most common of the primal elements, but it is an enigma. The product of a burning gas, it is colorless, yet seems to have color. It can be a flowing liquid, an evanescent mist, a cold solid. As a delicate, featherweight snowflake it quickly melts into liquid in my hand, yet as glacial ice it can carve and polish solid rock. Water is found in the soil, sky and living tissues of all pants and animals. It is an essential part of all aquatic and terrestrial ecosystems. Water comprises nearly 70 percent of the biomass, or total weight, of all planetary life forms. It makes up 85 percent of my brain, 10 to 15 percent of my bones, and about 80 percent of my blood. In a reductionist sense, I am simply a vessel for moving water from place to place.

My friend and mentor Freeman Tilden, the father of the art of interpretation, bemoaned the perversion of the meaning of amateur. He said that "to most people it means a dabbler, a bungler, a producer of something inferior." Yet, it originally described someone who was doing something for the love of it, not for material gain, fame or notoriety. I was a "professional" naturalist for The National Park Service for more than thirty years, but I was really an amateur, and a very happy one.

According to eastern philosophers, the laws of Nature and its processes—the machinery of the physical world—is Tao or The Way. They believe that in all things that exist there is form and essence. Form is palpable, it can be seen, felt, weighed and measured. Essence is intangible, it cannot be touched, counted or timed yet it exists, and it is that which animates and sustains form. Too often in our encounters with Nature, in our haste to keep to our schedules, or with our concentration on the past or future, we fail to be mindful of the present, the possibilities of the moment. We see the form but fail to experience the essence of place.

Practitioners of the ancient Chinese art of Feng Shui believe that the spirit or atmosphere of a place influences our physical, psychological and emotional health. Feng Shui masters are sensitive to the essence of things, and they manipulate, combine and blend the parts of living and working spaces to enhance their influence on people.

Natural process is like a Feng Shui master, arranging all of the elements in the house of Nature in the most harmonious way. In places such as Yellowstone and Everglades national parks, nature has woven complex fabrics of living organisms and physical environments. In those large ecosystems—and smaller ones too—there are shapes hard and soft, large and small; networks of lines crossing lines; angles folded upon angles; circles within circles; a full spectrum of colors. These elements form the basic pattern of natural order that Zen philosophers refer to as Li.

As I grow closer to my expiration date, I remember living among the primeval forests in Sequoia National Park, many years ago. It was a lesson in perspective and scale, a meditation on the transience of human life, the sovereignty of nature and the folly of believing that we have dominion over wild things. Many of the Brobdingnagian trees were old but still had a thousand or more years to live. Paul Bunyan would have been at home there.

Edward Abbey said "The purpose of the giant sequoia tree is to provide shade for the tiny titmouse." He was reminding us that small things are important parts of nature too. An ecosystem where giants dwell would be inefficient and incomplete without the slime mold, the newt and the copepod. Solid stone, born of particles of sand, is crumbled by living veneers of tiny lichens. A drop of water holds the promise of a river. However large and old living creatures grow, they all spring from microscopic cells and help make nature's engine run. These truths give solace to me in my old age.