BOOK REVIEW : A Moving Testament to Nature’s Beauty : THE FOUR-CORNERED FALCON: Essays on the Interior West and the Natural Scene <i> by Reg Saner</i> ; Johns Hopkins $25.95, 288 pages

“Western terrain,” declares Reg Saner in “The Four-Cornered Falcon,” has “long stirred in me a fairly passionate impulse to witness.”

Saner’s testimony comes to us in the form of 14 essays on the “interior” meanings of the American wilderness. Some of the chapter titles may suggest a warm, fuzzy, New Age approach to the natural environment: “Wind,” “Snow,” “Sacred Space,” “The Mind of a Forest”--but the fact is that Saner brings a hard edge and a high polish to these essays, which are more concerned with philosophy than with pretty scenery.

A poet at heart and by trade, Saner is perfectly capable of giving us rich, intimate and evocative descriptions of the canyons and peaks that he knows so well. Now and then, we come across a burst of prose that scans as free verse.

“All around me/Hundreds of boxcar rock chunks/sit on granite plates,/each wide as a world-turtle,/mottled by centuries-slow drizzles of lichen. . . ./They return my look with disdain:/’Do you actually pretend to exist ?’ ”

But “The Four-Cornered Falcon” is decidedly not a pastorale; rather, it’s the work of a cool intellect operating in the high classical mode. Invoking Genesis and the Bhagavad-Gita, Saner dresses up his musings with snatches of Latin. And he uses the encounter between a solitary human intelligence and the ineffable meanings of the wilderness as a focal point for musings on art, language, science, technology, love, sex and war.

At its most successful moments, “The Four-Cornered Falcon” convinces us that American wilderness may be regarded as the nexus of ambition and destiny on a nearly cosmic scale.

For example, the essay titled “Technically Sweet” is a fugue-like contemplation of the Anasazi pueblo dwellers, the victims of Dachau and Hiroshima, and the bomb makers of Los Alamos. Summoning up the ghosts of Robert Oppenheimer, Niels Bohr and Edward Teller, Saner shows how these over-civilized men used the pristine desert of the Southwest as a place to fashion a diabolical technology that has changed the fate of humankind.

“The solace these people take in the beautiful Pajarito Plateau and its setting,” Saner writes, “will help them make areas of the West, and our Earth’s northern hemisphere, unnaturally radioactive for the next 24,000 years.”

Saner occasionally waxes metaphysical and even mystical. The geographical features of the Grand Canyon strike him as “steadfastly evanescent, without judgment, wanting nothing, holy.”

And yet he insists on drawing us back to the here-and-now, reminding us that nature can be indifferent and dangerous, as when he describes the efforts of a search-and-rescue team to bring down a climber from the Colorado Rockies.

“What their search finally turned up was a young man in the prime of life,” he writes with characteristic stinging irony, “except for being dead.”

Saner apparently feels enlightened but not ennobled by his experiences in the wilderness. In fact, he appears to regard the austere beauty of unspoiled places as a reminder of the essential meaninglessness (or, even the malignity) of human enterprise.

When he sets out on a hike through “granitic Colorado,” Saner describes it as “a radical enterprise: to spend at least one day of my life as if it were precious.” Day-to-day life in an urban setting, he seems to say, is a sorry waste, and the wilderness “bestows huge insignificance on anything alive and in motion.”

The book begins and ends with Saner’s reflections on Pliny the Elder, who figures as a symbol of Western civilization and its sometimes catastrophic intersection with the natural environment.

By the end of the book, Saner imagines Pliny--”our first globally curious author”--as a ghostly observer riding a satellite around the Earth and surveying what has become of human civilization, which Saner dismisses as “networks of sperm-and-egg sequels.”

“In effect, he’d have been staring down at what Roman law--his culture’s most durable gift to posterity--had done much to make possible,” Saner writes. “ ‘O!’ he could help exclaiming; which even in Latin is ‘O!’ ”