Red Auerbach hardly knows where to begin. The Boston Celtic president has been so smart recently, after being told for two years how dumb he was, that even he finds it a bit disgusting.

Was his best move the hiring of Bill Fitch as coach after Fitch had been fired by the nondescript Cleveland Cavaliers?

Was his coup de grace the sweet-talking of M. L. Carr into green Celtic uniform even though the free-agent forward was offered bigger bucks by other NBA teams?

Or was Auerbach's best brainstorm his gamble in drafting Larry Bird as No. 1 pick of year early in '78 -- then weathering a year-long $3.25 million negotiation with Bird's agent?

After all, five NBA teams bypassed Bird before Auerbach pounched, puffing philosophically, "A year goes by fast."

At the moment, with the Celtics' 19-6 record the best in the NBA, Auerbach's acquisitions look like a glorious dead heat.

A year ago, as Auerbach walked to his midcourt Garden seat, he heard people say, "Auerbach really butchered the team." Now, to his face, they say, "Red, we're sure glad you stayed."

It isn't everyone who gets to go from genius to dunce to genius to dunce, and then back to genius -- all inone decade. That's been Auerbach's wild progression from '69 to the present.

Right now, Auerbach praises Fitch most -- part of his campaign of insisting that he isn't looking over the new man's shoulder. For the first time since Auerbach retired from coaching in '66, his nonintervention protestations are probably close to being the truth.

Fitch is the first Celtic coach since Auerbach who wasn't a former Celtic.

"I just ran out of Celtic coaches," says Auerbach with resignation, having replaced Tommy Heinsohn with Satch Sanders, then Sanders with player-coach Dave Cowens last year.

"We had to go outside the family . . . best decision I ever made," says Auerbach. "A generation in people is 20 years. A generation in basketball is six years. No matter how successful you are, you have to have the flexibility to change approach.

"Nothing in coaching is worse than being monotonous."

So the old Celtic system is gone. No more No. 15 play -- the triple pick for John Havlicek. No more No. 6 -- the setup for Cowens' jump hook. Now it is strictly Fitch's system.

Nonetheless, the old fundamentals and the new are still the same. Fitch, like Auerbach, is an anomaly among pro coaches: a teacher who deals with minutiae first and overviews second.

"The NBA is not a fundamentally sound league," says Auerback. "College coaches, who come up with most of the new ideas, know it. They respect very few pro coaches.

"In the pros, you hear a lot of talk about overall concepts. But I always thought you either had to build from the pieces to the whole or from the whole back to the pieces, I was always a pieces-to-the-whole man."

So is Fitch. He is a fanatically discimplined and meticulous man who disdains ruminative jabber about the theory of the game and prefers infinite attention to detail.

Fitch, for nine years coach and general manager of the Cleveland Cavaliers, not only takes a film projector everywhere on the road, but has a vast network of NBA contacts who give him numbing trivia about games all over the country.

"I saw that Scott Wedman scored 38 points on the West Coast last night," a friend will say to Fitch.

"Yeah, he got 17 of them in the fourth quarter off Walter Davis. They posted him up a lot."

Good Lord how do you know that?"

"I called one of my friends who does radio in Phoenix at 2 a.m.," Fitch will answer.

That is one side of Fitch -- the fellow who never leaves the house with a wrinkle in his attire, and who has a passion for shopping in malls on the road in search, he jokes, of the perfect pair of slacks.

The question with Fitch, however, is always, "Which Fitch?" There seem to be several of him, at least.

Without doubt he is the funniest NBA coach in memory. "I got ejected early tonight so that I could meet with my gag writers," said Fitch last week. "(Johnny) Carson would be proud of some of the stuff I've dreamed up."

The Celtics never know what he will say next. Spotting a despondent Cedric Maxwell slumped on the Celtic bench at practice the morning after a particularly poor performance, Fitch approached his No. 2 scorer.

"Morning, Cornbread," said Fitch. "I see you're practicing your game plan from last night."

"????," said Maxwell's face.

"You're sitting on the bench," explained Fitch.

"A month ago, he would have panicked if I had said that," said Fitch later. "But now the players are learning how to take me. Cornbread wanted a word of encouragement from me, so I told him, 'You were absolutely terrible last night. There's no excuse for you ever having a game that bad.'

"They have to understand that the coach gets paid for being critical, not telling them how wonderful they are.

"I've never known a good player who couldn't take a tongue-lashing -- so long as it's about a basketball situation -- then turn around and go to dinner with you 10 minutes later.

"What the egos in the NBA need most is somebody to tell them the truth. This league is full of guys who look like Lon Chaney who wake up in the morning, look in the mirror, and convince themselves that they're Clark Gable."

Fitch and his players have a warm rapport, but as one long-time Celtic observer says, "He's the first coach here since Bill Russell that the players view with a healthy fear."

Above all, Fitch is a chronic, wry pessimist, always foreseeing the worst. "I had a 16-4 start once before," he says. "By March, Blue Cross wouldn't touch us. I had a guy injure himself getting off the bus. We started the playoffs with a team that was on a last-name basis."

On one subject, Fitch has a terrible time working up his famous negativity -- Larry Bird.

Is it true that the central cog in the Celtics is the rejuvenated Cowens. "We're still a Cowens-oriented team -- he's the hub, no matter how much people talk about Bird," says Fitch. "I know how this car was put together."

But Fitch also knows that Bird is the fountain from which all good surprises spring. Cowens is a known and steady factor. Bird is a kaleidoscope of fresh colors.

"Larry, right now, in his coach's eyes, is paying the price of having unlimited potential," says Fitch. "I'm never going to be totally satisified with him."

Then Fitch grins: "I'm determined to find at least one thing that he does wrong in every game."

Bird eats up the criticism with a spoon. Fitch is one of the few NBA coaches who is such a technical fanatic that he is actually qualified to pick at Bird's feathers.

"I'm gettin' to hate videotape," drawls Bird. "Coach can tell you everything you've done wrong."

Overall, Fitch may be the only one who has been a match for Bird, who leads the Celtics in scoring (19.1), rebounding (10.1), steals and is second in assists (4.5) and blocked shots.

Bird tries his best to be modest, praising his mates and all the great opponents he is meeting for the first time.

But get down to brass tacks and he can't tell a lie.

Has he seen anything, even one trick, that surprises him?"

"Can't say I have," he says almost inaudible.

"Guys my age (22), we're probably the first ones who got to grow up watching the NBA in slow-motion replay since we were little kids. I don't see how you could keep much of anything a secret."

What does he think of the NBA as a whole?

"It's a pretty good brand of basketball," he says.

Just pretty good -- nothin' special. If somebody returning from Tibet discovers a higher league, says the Himalayan Hoop Heaven, Larry Bird is ready to go.

"I'm enjoying myself," says Bird. "I always have fun . . . but I don't like to show it much.

"The Celtics know basketball. They appreciate the little things and pick up what you're tryin' to do.

"We're playing well, so you can try to create more . . . take shots you might not otherwise take. You can't be as loose and free when you're losing."

Boston fans still haven't totally picked up what Bird is "tryin to do," even though they gasp continually and give him standing ovations -- the first one just eight minutes into his first game.

"They're good fans," said Bird, a trace of a smile showing, "but I can't tell yet if they'll be as good as Indiana fans. Back home, by the end of the year, I had 'em ready for anything. They'd know what I was about to do.

"When they're anticipatin' with you, that's the best thing. Folks deserve a good show for their money."

Acutally, NBA life may suit Bird better than the world of academics.

"I hate to practice and I love to play," he beams. "it's good when you can get revenge so quick after a bad game. I've lost a few pounds, but I'm ready to challenge the schedule. I think I can, 'cause I love this game so much. I ain't quick and I don't jump that well. But I can play."

Bird has even made the beginnings of a peace with the world at large and its nosy representatives -- the press. And he is learning to protect himself. i

Around French Lick, a man isn't judged by whether he has holes in his socks, but by the quality of his labor. But that ain't the city way. So when Bird spied a hole as big as a quater in his black socks this week, he casually reached down -- looking the other way as he would while making a blind pass -- and folded the sock overso the hole disappeared and the dozen reporters around him didn't have one more quaint little tidbit to josh at.

Bird's wisdom is nonverbal. He knows the secret of waiting just a second or two for 10,000 eyes to move away from him before he makes his little gesture of communication with a teammate. Consequently, he never hot dogs, never plays to the crowd, never alienates anyone. He's a purist.

The most delighted person with Bird's personality is Auerbach. "That's the surprise," he says. "As a person, Bird's more than we expected.

"He's easy to coach, not cocky. Knock him down and he gets up, comes after you and knocks you down.

"And he's got a nice, dry humor . . . beat me out of a buck the other day," said Auerbach.

"We were in one of those gyms with six baskets. He says to me. 'Bet I can bank one in from here,' and he nods to the basket 40 feet away. I said, 'A buck you can't.'

"So he grins, turns around and we're standing right under one of the other baskets. He lays it in and says 'I didn't say which basket. Pay up?'"

Auerbach, who has already shelled out millions, only pulled that ancient trick 100 times himself.

"I warned him," says Auerbach. "I'll get it back." What the club president really means is that he is following one of his oldest rules: You don't handle people. You get along with people."

The force behind the Celtic flame is still Auerbach, the Jewish leprechaun with the instant intuition.

The heart of Auerbach's professional life is his office in the bowels of Boston Garden. It is as good a symbol of the Celtics' perpetual rebirth as any.

"I think this office has acutally signed players for us that we might not have gotten otherwise," says Auerbach.

The first two that might come to mind are Bird, who was drafted a year early in '78 and might have gotten more money by waiting for the '79 draft with a different team, and Carr, who was a free agent.

Perhaps no words can describe the infinite clutter , the muddled charm and the sense of a total unified personality that emanates from Auerbach's pack-rat den.

"It's like home," he smiles. "Comfortable and full of junk."

All around him are small signs that say, "Think." "I love to watch people," he says. "And I love to shop."

Havlicek and (Don) Nelson -- I taught 'em how to shop -- a jade chess set in the Far East . . . scrimshaw from New Bedford . . . carved ivory in Burma. I like Royal Danish china better than Royal Copenhagen. The painting on the Royal Copenhagen is very ordinary.

"But the main thing about shopping," concludes Auerbach after covering most of the explored world with his anecdotes, "is that it's only fun when you do it on a limited budget. I don't buy to sell. And I'm never extravagant."

And that, of course, applied to men rather than china or chess sets, is the core of the Celtics success.

Auerbach remains the king of the shoppers, the prince of far-sighted bargain hunters.

"I've always had to make do with a little less," says Auerbach. "Even when I coached at Roosevelt High in Washington in the '40's I remember stopping a big kid in the hall and saying, 'I want you out for basketball tomorrow.'

"Unfortunately, the kid wasn't very good. His name was Bowie Kuhn and I cut him two days later. I understand he's done well since."

"Since I've been with the Celtics we haven't had a draft pick higher than the fourth man in 25 years -- and "I never spent a dime for a player.We develop our own people and we stick with 'em."

Once more, Auerbach has taken the reins of the Celtics firmly in his hands -- shopping for a free agent that he had befriended years before, signing a flighty Bird with the aid of that cluttered office and some malarkey.

Red Auerbach is a venerable institution now. Instead of going on road trips, he returns home to Washington. Sometimes he misses a practice so he can lecture at Harvard.

He is a man who looks semiretired, relaxed, like an unharried patriarch of his Celtic clan.

So how does he fell, watcing his handiwork begin to fall in place once more?

Red Auerbach points his cigar for emphasis, and suddenly looks rather young.

"I tread," he says, "with fear and trepidation."