It gets spooky out here in December: a field of smashed pumpkins, huge gray skies with the horizons orange even at noon. The summer people have forsaken the shingle mansions and the Hamptons revert to duck farms and potato fields planted in rye for the winter.

The wind nags at the hanging blinker by the turn for Peter Matthiessen's house. At the corner by his towering, tangled privet hedge, a woman careens past in a four-wheel-drive Chevy Blazer, way too fast. The pond down the road from Matthiessen's place is high, very high, brimming like mercury, the wind tearing at it.

Leaning against his fireplace in writer's fatigues (moccasins, Levis, black turtleneck under khaki shirt), Matthiessen says: "It builds up, the water gets higher till it bursts through the dunes and pours into the sea in one huge rush." And his hands scramble into sudden, extravagant flight.

Why? Something is trying to be meant here. Matthiessen has made a career of escaping-he might say returning-to the wildest ends of the earth; his Zen Buddhism aims at bursting him through to oceanic awareness. His face bears the lines of chronic preoccupation, in any case, "like a memory in the ocean emptiness," as he wrote in his last novel, "Far Tortuga."

He cracks a Brazil nut. A nimbus-white cat drifts past the baby grand piano, and a silence nuzzles into the conversation in his big, spare living room that was once the garage for an estate house long since burned down. He is tall, lean, hard, shy, with blue eyes, curly brown hair and little age lines perpendicular to lips which scarcely move as he talks.

At 51, Matthiessen is everything the American writer is supposed to be: an educated (Yale), well-traveled (all continents) explorer of realities both inner (LSD, mescaline, Zen Buddhism) and outer (everything from plights of Cesar Chavez's farmworkers to erosion in Nepal). He became a cult figure after his fourth novel. "At Play in the Fields of the Lord." He is The Man of Experience who has Done It All, from commercial fishing off Long Island to attaining the enlightenment instant the Zen Buddhists call satori. And he moved to the Hamptons in the mid '50s, before they became literary.

The problem is that the quest for experience, for a lot of 20th-century writers, has only served to mask a more desperate or doomed struggle-the quest for meaning. With every book of his 14, Matthiessen has moved further into this quest.

And, at last, he has established himself on a national best-seller list with "The Snow Leopard."

It hardly seems best-seller fare-the reviews have been mixed and it mingles thoughts on Zen Buddhism and memories of his second wife's dying with the amount of his trek to the wildest recesses of the Himalayas. Ostensibly he was seeking glimpses of the rare snow leopard, the blue sheep and even the yeti, or abominable snowman.

But he writes: "To say I was interested in blue sheep or snow leopards or even in remote lamaseries was no answer . . . How could I say that I wished to penetrate the secrets of the mountains in search of something still unknown that, like the yeti, might well be missed for the very fact of searching?"

So the spookiness out here, which manifests itself most conspicuously as a kind of muscle-bound loneliness, doesn't bother him at all, he says a few minutes later, sitting down to a lunch of flat bread which he stuffs with avocado, cucumber and mushrooms fried in butter by his friend Maria Koenig.

"You're asking the wrong man about loneliness," she says with rich exasperation.

"It's great out here," he protests, peeling thin lips back to boyish smile. "Beautiful out here in the winter. The days are unbroken. Nobody comes by. i get more work done in these months than in all the rest of the year put together."

Besides, his kind of solitude can clamor and shove like a rush-hour subway crowd. As he puts it, burnishing the vowels with a touch of upperclass accent, "There's a resonance in things, I love mystery and I think we close ourselves off to it. I've just been working with a lot of American Indians, writing about our transgressions of our sacred lands. With them, everything means something - a flicker lands (Matthiessen's hand flutters by his shoulder) and it means something."

Sure enough, only a few days ago Matthiessen went to telephone a friend in California, and when he picked up the receiver she was already on the line. These things happen to him. But, as he's quick to point out: "There's nobody, if you take them aside and ask them, who will say they haven't had some experience like that."

'A Lot of Power'

But they lack Matthiessen's druidical intensity, an animism which mingles with scientific detachment - he calls himself a "semi-trained field naturalist" - to create a tension which ranges from solemn to merry to fey.

"The Snow Leopard" fairly jangles with mysterious significance, with a potential for sudden revelation which keeps eluding Matthiessen.

"I had a lot of power then," he says. "These things happen to you when you have power."

The power came one day during meditation before his wife, Deborah, died. "I let my breath go and gave myself up to delighted immersion in this Presence, to a peaceful belonging so overwhelming that tears of relief poured from my eyes . . ."

The marriage, which had been disintegrating, grew strong again as the cancer claimed her.

"Then I lost the power, it went away," he says now. And the search began anew. A biologist friend invited him to go to the Himalayas, yet another step into the unknown.

He was ready for it. Matthiessen was born into the generation which grew up through the major dislocations of 20th-century America: the Depression, which he weathered nicely as the son of a rich Connecticut architect; then World War II, which he caught the tail end of as a Navy enlisted man, after graduating from Hotchkiss, a Connecticut prep school.

The Yale he came back to was being democratized by veterans. In 1951, he went to Paris, where America's last generation of literary expatriates was scraping the cultural bone whose meat had gone earlier to Hemingway, Joyce, Fitzgerald et al.

At a bar in Montparnasse, a discussion of the pretentiousness of most literary magazines led to the founding of The Paris Review, which survived with staff such as George Plimpton, a Matthiessen friend from St. Bernard's elementary school in Manhattan, and contributors such as William Styron, James Baldwin and Terry Southern.

In late 1953, Matthiessen and his first wife, Patsy Southgate, moved to the Hamptons, where he worked as a commercial fisherman, writing in the winters.

"I don't think I could have done my writing without the fishing. I needed something physical, something non-intellectual."

"I'd come here as a boy," he says, "on summer vacations during the war, so I felt at home."

It was a move which would become a mass migration in the 1960s as countless children of the higher classes fled establishment expectations for a reality which usually resembled summer vacation lived all year round.

His first novel, "Race Rock," appeared in 1954, describing the interaction of three aimless upper-middle-class young people with a fourth, who is a natural man of action. His next novel, "Partisans" (1955), showed a young journalist grappling with the hard realities of revolutionary action in the poverty of the Paris proletariat.

Man in search of meaning: After breaking up with his wife, in 1956, he loaded his Ford convertible with books, shotgun and sleeping bag and set off to examine the last wildernesses of America. In 1959 he published "Wildlife in North America" to high praise.

His quest carried him further, wilder, stranger: the South American jungle for "The Cloud Forest," then to a tribe in New Guinea for "Under the Mountain Wall"-the same expedition on which Nelson Rockefeller's son Michael died.

In 1965, he returned to fiction with "at Play in the Fields of the Lord," which won mixed critical reaction but an enthusiastic following. The book is wonderfully funny, for one thing, showing the clash of missionaries and down-and-outers in the South American jungle. For another, it reflected Matthiessen's delvings into the ego-dissolving wonders of LSD and mescaline.

"And yet, and yet . . ." he writes in "The Snow Leopard," "an 'I' remained, aware that something-was-happening, aware even that something-was-happening because of drugs. At no time did the 'I' dissolve into the miracle."

And he came to believe "the one danger of the mystical search: There is no way back without doing oneself harm. Many paths appear, but once the way is taken, it must be followed to the end."

Almost inevitably, he came to Zen, in which the ultimate strangeness of the universe becomes ordinary in an instant, "the apprehension of the infinite in every moment," he writes, quoting the old Zen saying:

How wondrous, how mysterious!

I carry fuel, I draw water.

"Goldenrod," Matthiessen says, pointing to what once must have been a lawn as he walks-sauntering, almost gliding. He feels good today, having turned down a cup of coffee after lunch, saying, "I'm already pretty wired up."

Past the goldenrod lies his studio, a small white clapboard house with a peaked roof. The clouds grind overhead, the light seems to seep away throught that huge secluding gloom of the privet hedge.

"The studio was originally the playhouse for the children of the estate," Matthiessen says.

He opens the door to an L-shaped workbench along two walls, an IBM typewriter, an Eames chair and ottoman ("a little grand for me, but it was a gift") and a dry, light, pungent smell-not as dry as an attic, lighter than inside a canvas tent: cozy.

'Maps and Rocks'

"Maybe it's the oak, he says pointing to a low table rough-cut from old gray beams and bearing souvenirs of his world wanderings, souvenirs which, on second look, are astonishingly ordinary: skulls of a green turtle (from his time in the Caribbean researching "Far Tortuga") and a javelina, vertebra of elephant, coral, a handful of polished stones-and some rocks, large and gray, just rocks.

"They're New England sea rocks," he means to explain, one gathers from his tone, "and those are slate from the Klamath River. I like rocks. I especially like wild rocks."

Asked if he can find any difference between these and all the other rocks in Long Island Sound or the Klamath River, he says:

"Yes, but I don't think I could explain it."

On the wall is a picture drawn by his son Alexander, now 15 and living with him, of Matthiessen on a Himalayan mountain not seeing the snow leopard behind him.

And a drawerful of maps: "i love maps. Maps and rocks."

Upstairs, in a loft, Matthiessen has covered the floor with the Japanese mats called tatami. On it lie his meditation cushions, black, neatly stacked before a huge, round window-richly austere, the air ringing even with this gray light.

"I've been feeling very much burdened down by accumulation," he says. "You realize there are literally millions of objects I own if you count the nails and broards. I've been trying to get rib of things."

Not that anything here behind the privet hedge has even hinted at a happy wallowing in materialism. Were the rooms not so space, the furniture in them might look shabby.

'Ups and Downs'

Certainly the truth shall make us free, but not necessarily confortable and jolly.

"I have my ups and downs," Matthiessen says, staring with an intense, close patience. "I can be very merry when I'm up," he says, flashing a smile to illustrate, a bony shoulder rising with one of his sporadic gestures, a skewed extravagance of hand flying through the air. "But I have other times too when I wake up early in the morning, wake around 4:30 and it's as if I had a bad dream but I can't remember what it was but I can't get back to sleep either. . ." He thinks about it. "It's not very pleasant. My mother had it, too. They have all these drugs for it, but I've seen what they do to people. I'd kill myself before I'd take them."

And not that Zen will end those down times either. "We assume enlightenment will solve our failings, but it doesn't. It solves faith. It solves doubt."

Way up, way back in the Himalayas, Matthiessen was happy. Page after page of "The Snow Leopard" attest: "The sky gleams, and the rigid peaks resound. The beauty of the Namdo Pass opens the mind. . ."

But then he has to come back: "Coming down, coming down-a dream of falling, in a machine no longer in control."

The world still resonates, but the omens are horrid-a fear-crazed pony, for instance, skidding on sheet ice, "a grim portent," Matthiessen writes, "of approaching civilizations."

And he hasn't seen the snow leopard. But not many of us do. And as Matthiessen himself put it, quoting Herman Hesse at the beginning of "At Play in the Fields of the Lord": "The way to innocence, to the uncreated and to God leads on, not backed, not back to the wolf or to the child, but ever further into sin, ever deeper into human life."

Deeper . . . something trying to be meant . . .

It's 3 o'clock now, but it's been 3 o'clock all day. Down the road from the privet hedge enclave, that gloomy pond still brims, the wind knocking the cattail heads nearly to the water, everyting waiting for the final rush to the sea.