On Earth Day, 1970 -- the first Earth Day -- I joined several hundred other University of Washington students in a line in front of the Student Union Building. There we waited for forestry students to issue each of us a tree to plant on a vacant lot near Husky Stadium.

I had already planted more trees than I care to think about as a summer worker in the Coeur d'Alene National Forest, so I mentioned that no one was bothering to cover the roots. This gave the seedlings little chance of survival. A budding forester leaned close and said, "Don't tell the others -- it will spoil the spirit of the thing." The trees died in a week. The hoped for forest is now a gravel parking lot.

Soon after, I read a book with a better grasp on the relationship between spirit and reality as they relate to environmentalism. A Sand County Almanac, by Aldo Leopold, was completed in 1948 -- the year he died of a heart attack while helping neighbors put out a brushfire near the central Wisconsin farm for which he named his book.

Since his death, Leopold and his book have become icons of the environmental movement. Classics become so by clarifying ideas their readers bring to them, and by raising questions that recur during later experience. So it has been with A Sand County Almanac and me.

Leopold bought his farm cheap, because early farming practices had eroded its soil. He puzzled about why this happened. Farmers invested in machinery and buildings. Why didn't they also invest in the soil that kept those assets productive?

Perhaps because erosion control often requires cooperation by many farmers. But so did the schools and churches they commonly built as community projects. Why then, did they neglect the soil, upon which their communities also depended?

An old tree falls on the road to his farm. As he writes about cutting it, he comments on its greater significance beyond being a nuisance (blocking the road), and a material resource (firewood). The growth rings tell the history of the region. Narrow rings mark drought, broad rings tell of lush times. These he relates to the region's recorded history.

Later, he talks more about using the land by learning from it, in addition to satisfying material needs and producing market products. He enjoys shooting upland game birds and waterfowl. Plover on toast seems to be his favorite game recipe. Then he notices the plover's elaborate mating ritual and takes fewer (but he still shoots a few).

The book goes on this way, matching concrete experiences with broader topics. I won't spoil your reading by revealing others.

Leopold began his career in 1909 as a young forester in the Southwest. That career spanned the peak of America's use (and frequent abuse) of natural resources; the economic boom of the 1920s, the Depression and dust bowl years up to World War II.

It also spanned the first environmental movement. Beginning in the Theodore Roosevelt administration, the conservation movement created much of the institutional and intellectual structure upon which modern environmentalism is based. Included among its accomplishments are the modern professions of forestry and wildlife and fisheries management.

It would be interesting to hear Leopold's comments on the second environmental movement, which began in the 1960s. He would be impressed with the prominence environmentalism has gained in politics and public opinion. Likewise with its tangible accomplishments, including expansions of wilderness, suppression of DDT, restoration and management of fish and wildlife populations, to name a few.

Another matter is what he would tell his disciples in Earth First! about "monkeywrenching." Or those in PETA (People for the Ethical Treatment of Animals) -- particularly, the PETA delegation that appeared four years ago at several Spokane elementary schools. They dressed as carrots, and told eight-year-olds that eating meat was not only murder, but dangerous to their health.

In 1996, shortly after moving back to Spokane, I had the task of representing hunters on a panel in Montana, where environmentalists were debating the merits of hunting bear and cougar. Previously, a national Sierra Club leader had lamented how more Americans appreciate the accomplishments of the environmental movement than admire environmentalists and environmental organizations.

I picked up on his theme with the example of PETA's preaching carrots. My point being that "fringies," like the animal advocates, are exploiting, rather than contributing to, responsible environmentalism.

I soon learned how many "fringies" there were in the room. These included, I later discovered, several Earth First! members, then on federal probation for activities in the Mallard-Larkin area of Idaho. Amid their screaming, I did, however, notice a few heads nodding agreement. One brave soul actually rose to my support. Others commented favorably, but in private.

I like controversy, so no harm was done. And the drive back to Spokane allowed me to reflect on the experience. It is easy to preach moderation and balance to environmentalists, but it is harder for those within the movement to practice it. The very success of environmentalism has made it the same kind of untidy coalition one finds in both of our major political parties.

The tension between extreme environmentalists and their more moderate brethren -- along with the even greater tension between all environmentalists and those supporting industries that rely on natural resource extraction -- may seem a new dynamic, but it's not. Aldo Leopold foresaw it back in the 1940s, and his case for thoughtful, moderate environmentalism as set out in A Sand County Almanac stands as an eloquent and timeless treatment of the subject.