IN each of his 20 books of reportage and fiction, Peter Matthiessen converts the act of writing into a partly muscular, partly moral event. His lean prose moves firmly down the page's blank face and onward to book's end, describing perhaps how he once climbed a Himalayan summit or canoed through an Amazonian forest in search of some elusive truth. A highly honest writer, he does not commit to paper what first he has not sought, tried, and found for himself. The tie that binds Matthiessen's fiction and nonfiction writing into one voice is the vital question of wilderness and its disappearance from both landscape and human spirit. ``I try to plead for what is being lost,'' he explains, ``so later I won't have to eulogize what might be dead.''
An intersecting concern for native lands and native peoples seems to underscore all his work, whether in Peru with ``The Cloud Forest'' and ``At Play in the Fields of the Lord,'' in Africa with ``The Tree Where Man Was Born'' and the forthcoming ``African Silences,'' or, in their own way, even along the Atlantic Coast with ``Far Tortuga'' and ``Men's Lives,'' his 1986 account of Long Island's dorymen.
Matthiessen makes the most of chance opportunities to travel to distant destinations. Following invitations to join a zoological expedition in Nepal, a shark hunt on the high seas, and an ethnographic field study in New Guinea, he fashioned nature travelogues that are equally literary, scientific, and personal. His highly plotted account of Stone Age tribal warfare in ``Under the Mountain Wall,'' for instance, was admired equally by Truman Capote and academic anthropologists.
Given his reputation and higher output as a writer of nonfiction, Matthiessen surprisingly says he feels he might rather have followed his original course as a novelist. ``Nonfiction started out only as a way to put bread on the table,'' he says. ``One way or another I've done a lot of it over the years, but I'd like to keep writing fiction from now on.''
``Killing Mister Watson,'' only his second novel published since 1965, appeared last year to great acclaim. Based on a legendary figure who lived at the turn of the century in the backwaters of the Florida Everglades, where Matthiessen spent much of his youth and often returns, the book reconstructs the testimony of semi-fictive characters who might have witnessed Watson's murder.
Writing in the preface, and aptly summing up the need for plausibility that underlies all his fiction, Matthiessen notes that ``almost nothing here is history. On the other hand, there is nothing that could not have happened.'' The book's reliance on strong characters who speak for themselves in an indelibly regional dialect brings to mind both the experimental discourse in his previous fiction and his use of other people's keenly heard testimonials in his reportage.
THAT his 10th book of nonfiction, ``In the Spirit of Crazy Horse,'' should fill a bookstore window in New York and land on the San Francisco bestseller list this month, eight years after its initial publication, is perhaps cause for wonder. That in the meantime it was forced by a bitter libel suit into a detour to the US Supreme Court, where an author's basic right to free speech was reaffirmed, is certainly cause for celebration - even from someone as serious as Matthiessen.
Not one prone to distraction, Matthiessen emerged from his own legal ordeal still firmly set on his original purpose.
A Lakota Indian named Leonard Peltier, a leader of the American Indian Movement (AIM), had been found guilty of two FBI agents' deaths in a 1975 shootout on the Pine Ridge Reservation near the Black Hills of South Dakota. By writing ``In the Spirit of Crazy Horse,'' which examines the facts of the crime as well as the long-standing government persecution of AIM members, Matthiessen sought to bring Peltier's questionable conviction to public attention.
``I didn't start out to write a book about Peltier,'' he says, ``and certainly not one of 600 pages. But the more I learned of the case, the more I knew it had to be publicized. I thought an Indian should be the one to do it, but when AIM leader Russell Means asked me, I said yes.''
He first started looking into the Peltier case when he was already deep into research for his 1984 book, ``Indian Country,'' dealing with various disputes between the government and Indians over their ancestral lands. While that book was written as an episodic travel journal, he knew the murky facts of the Pine Ridge incident and the details of Peltier's trial required a kind of sustained investigation he had never before attempted. Work on this superseded nearly everything else for five full years.
Even before ``In the Spirit of Crazy Horse'' first appeared in stores, however, a libel suit was filed against Matthiessen by a former South Dakota governor, followed a year later with another, filed by an FBI agent. Among other things, Matthiessen was accused of recounting historical charges and quoting damaging opinions about these two men ``with reckless disregard of the truth.'' The plaintiffs tried to distinguish between ``responsible'' sources, such as editorial pages and court records, and the te stimony of ``disreputable'' persons, such as the AIM members he extensively quoted.
Both cases were eventually dismissed and the principle of neutral reporting was affirmed. Matthiessen notes with irony, however, that defense witnesses in the Peltier trial, some the ones at issue in his libel suit, were discredited on the basis simply of their so-called ``disreputable'' character. And it was only by the testimony, later found to be fabricated, of a prosecution witness whose poor character was acknowledged by both sides that the government was able to win its conviction.
The 1991 reissue of ``In the Spirit of Crazy Horse'' contains an author's epilogue, in which he recounts his interview with an anonymous AIM member who admitted to being the FBI agents' real killer. On the strength of this and other evidence, Matthiessen feels confident that Peltier will soon be granted either a pardon or a new trial. Hollywood director Michael Apted, meanwhile, is preparing both a documentary and a feature film based on the case.
While advocating for the rights of an individual rather than for an endangered species or wilderness area might be new to Matthiessen, he is comfortable with the role.
``No, it doesn't seem a bit strange,'' he says. ``Peltier's spirituality and discipline show how to strike a balance between material progress and our deeper needs. Helping to set him free might do the same for all of us.''