Carl Yastrzemski's face looks as if it could have been chiseled accidentally by nature on some rain-beaten New England rock. It has the character, heft and substance of an old and pleasantly weathered stone.

In profile, his birdlike and slightly comic mug retains its underlying look of grim, peering intensity. His front teeth are jagged. His beard is a salt-and-pepper stubble, and his grizzled neck is a testimony to all of his 40 years, 10,392 at bats and 2,995 hits.

The Yaz, blessedly, is not a pretty bird, but a hardy solitary specimen that might endure on some bleak coastal fishing island of the Northeast. In fact, when Yastrzemski wants to put off the world, and the Boston Red Sox uniform, that is where he goes.

Once, when he was a glamorous $100,000 bonus baby of the '50s, Yastrzemski was a vain young peacock with gaudy plumage. Fortunately, he got over it.

Now, to put it bluntly, Yastrzemski has the sort of penetratingly vivid aspect that we assume has been forged and fought for under considerable pressure and even suffering.

One who had never heard of baseball might look at Yastrzemski, with the ancient face above the fiercely conditioned body of a young man, and conduct romantic fantasies about the lone survivor of a shipwreck or a man who had beaten some terminal disease.

It is an affliction of many major leaguers, especially those like Yastrzemski who were famous before they could vote, that they seem perpetually unformed, like teen-agers under glass.

In a locker room of smooth faces, mod hair styles, blow dryers, faddish clothes and carefully clipped mustaches, Yastrzemski looks as pleasingly incongruous as a gravy-brown Rembrandt in a gallery full of bright abstracts.

Once, of course, Yastrzemski was as weightless and unformed as any pampered player of his time. All the archives agree that he was, on occasion, a spoiled brat and clubhouse lawyer, the sort of moddy youth who might loaf, pout and even politick for front-office favors.

Whatever flaws Yastrzemski had then, he was punished for them many times over. Every adult must come to some difficult peace with the world; Yastrzemski had to come to terms with the city of Boston as its appointed heir to Ted Williams. That was a rougher deal.

For years, he was booed even when he hit a homer. Once, years after he had been both MVP and triple crown winner, he pulled cotton out of his ears in left field to show the Romans of the Fenway Coliseum the solution he had found.

Under the crushing pressure of being a New England institution that could never fulfill expectations, Yastrzemski gradually became himself, discovered his true motives and his bedrock relationship with his game.

Slowly, he began to play to please himself and to enjoy the texture of the game. But he also played by a ferociously solo, almost masochistic code.

The finished, polished and cured-with-age product-- a baseball masterpiece-- is currently on display.

On one hand, Yastrzemski loves and enjoys baseball as he never has before. "It's the most pleasure right now," he says as the baseball world watches his countdown to the 3,000th hit.

Part of that pleasure is pure stubborn vindication, the kind that the offspring of rugged Polish potato-farming stock would understand. For 15 years Yastrzemski was nagged that, except for his three 40 homer seasons, he had never been as sublime as New England wished him to be.

Now, the last critic is long since silent, with Yaz's bat stuffed far down his throat. After the age of 35, the point at which great demands no longer are permissable, Yastrzemski has piled one triumph on top of another.

After driving in 100 runs just three times in his first 15 seasons, Yastrzemski managed the feat at age 36, then again at 37. In 1977, he won his seventh Golden Glove, had a 1.000 fielding average and led his league in assists (16) for the seventh time-- an American League record.

For the last two seasons, Yastrzemski has been climing up the ladder of immortals until he has reached plateaus on the all-time lists that even he had no right to expect to reach-- fifth in games (2,843), 15th in hits, 10th in doubles (563), 14th in RBI (1,604), 13th in total bases (4,882), fifth in walks (1,630), 18th in homers (404) and 12th in extra-base hits.

Williams, similarly embittered in his youth, made an identical climb in his late years and it helped sweeten his disposition for life.

The difference with Yastrzemski is that he will never voluntarily give up baseball now that, at last, it is as much a delight as it once was a crown of thorns.

Williams' last years were a torment that he hated. Yastrzemski's are a torture that he seems to relish.

Both his Achilles' tendons are damaged so badly that there is fear that either could snap at any time. Yaz's legs must be taped so heavily from the lower calves down that he losses all feeling in his feet before the game begins.

"When I go to the plate now," he says in a voice so flat that it is difficult to understand his meaning, "I actually have to look down to see where my feet are in the batter's box."

For years, Yastrzemski has refused to pay attention to any bearable injury: it is part of his code to play until he is irreparably broken.

He has begged and cajoled doctors into giving managers a rosy account of his miseries. Last season, when wrist and back injuries reduced him to the point where he could only keep one hand on the bat at the instant of contact, he experimented with taping his hand to the bat in batting practice.

"Then I realized," said Yastrzemski, "that it wouldn't work, either. What was I going to do if I got a hit and tried to run the bases with the bat still taped to my hand?"

Once Yastrzemski was called the leader of the Red Sox Country Club-- the players who didn't hustle, Yastrzemski, who always bitterly denied it, has had the last word, though at a chilling price. "Yas plays every day," says trainer Charlie Moss, "as though it were his last."

As the countdown to 3,000 grows closer, the pain has reached the point in Yastrzemski's ankles that he must wear cleats on one foot and a tennis shoe on the other.

Yastrzemski has traded the sort of mental anguish that Carlton Fisk is currently going through for the simplicity of mere physical anguish. "I've gone beyond good sense many times," Yastrzemski says with a shrug. "Durability is part luck."

"You wonder how you can get so consumed by the flow of the season that you don't act rationally," says Fisk, currently the object of Beantown's wrath for benching himself. "You're up to your neck in the pennant race, so you say, 'Well, I can stand it one more day.'"

Yastrzemski can stand it, and has stood it continually for years, because he knows he has reached the status of being a living symbol of indomitable athletic fortitude. Long a silent man on the fringe of clubhouse camaraderie, Yastrzemski's courage has made him the heart and emblem of the Sox. He is not about to relinquish that position because of a small thing like waking up in the a.m. in pain.

Once painfully withdrawn, Yastrzemski talking to a marvel of baseball senior citizenry. No man could be more content than Yastrzemski talking to a groundscrewman or the clubhouse boy. He carries fame with becoming grace.

If a demand for deep emotional stability is one of the qualities that baseball stresses, Yastrzemski in old age seems to symbolize it.

"He seems emotionally identical every day," says Fisk. "We all struggle to use our energy and our talent the best way. Yas seems to channel all his positive thoughts, all his energy into useful things. Everything negative he seems to put behind him now."

"I'm just an average guy," says Yastrzemski, who is 5-foot-11, 180 pounds. "But I seem to have durability and adaptability. I'm willing to change myself.

"A lotta people don't want to admit to themselves that they're . . . I don't want to say doing things wrong . . . but not getting the best out of themselves. They're satisfied.

"That's because they are not totally honest with themselves."

Over the years, Yastrzemski has changed himself at the plate more fundamentally and more often than any star in baseball. A history of his stances and theories would make a book. "Making adjustments," he calls it. Other players marvel at the hidden gambler in Yastrzemski that makes him willing to fiddle with his success.

More fundamentally, Yastrzemski has been willing to carry that goal of "total honesty" over into the rest of his life. Perhaps no player of his time has "adjusted" so often and so well off the field.

Carl Yastrzemski's face is the map of that 20-year battle with baseball and with himself.

When he finally gets his 3,000th hit, Yastrzemski's crooked hard-won smile breaking through that implacable expression will be a symbol of his triumph.