Conan O’Brien, the 39-year-old talk-show host with a giant orange coxcomb of hair, was citing Master of the Senate , the latest hefty volume of Robert Caro’s Lyndon Johnson biography, to make a point.

“The really sad lesson of the whole thing,” he said, holding a Sam Adams at his cluttered desk in his cluttered office in Rockefeller Center, “is that he was just this guy burning with ambition, and he gets to the Senate, and the whole time everything he does is this Machiavellian drive to become President. And he’s brilliant in the Senate. He’s the greatest Senator of the 20th century-possibly of the 19th century as well-and he completely reworks the whole institution. And gets the civil-rights bill passed, and gets a lot of legislation passed.

“And then, you know, through a series of sad events he becomes President, which is his dream, and it ends up a nightmare. It’s a national nightmare and it’s his personal destruction and it kills him.”

Mr. O’Brien wore a serious look on his extra-large face, which with its choirboy optimism and canal network of tiny crags, was half-adolescent, half-middle-aged. “And so the point of that story is, I think I’m Lyndon Johnson. I think I have a huge cock. I think that I’m a very persuasive Texan. I think I’ve done a lot for civil rights.”

He smiled, then made his point.

“I think there are people out there who think of talk shows as a great way to get someplace else,” he said. “There are people who think, ‘I’ll do the talk show and that will get me into movies, and then I’ll become a figure skater.’” But Conan O’Brien said he didn’t want those other things. He wanted to be the host of what he called “this uniquely American thing”-a late-night comedy talk show. And he did not want to be just a talk-show host.

“I have one thing that I want to be,” he said. “I want to be that guy for my generation.”

Conan O’Brien wants to be that guy . And as he begins his 10th year as the host of NBC’s Late Night with Conan O’Brien with a new four-year contract, Mr. O’Brien has a reasonable chance of getting there. He owns the late-night talk-show giant-in-training gig, the 12:30 a.m. NBC slot that made David Letterman. Beneath his goofy, self-deprecating “I’m an ass” television persona is a supremely confident striver with a stone-cold-serious desire to succeed. “I don’t think it’s possible to want it to be good as badly as I want it to be good,” he said. “If you shot me in the lung just before I went and did a show, I’d still go out and make it as good as I could.”

On Sunday, Sept. 22, Mr. O’Brien will deploy that work ethic, his comedy and, maybe, his stirringly sexy string dance for the first really big television audience he’s ever had when he hosts TV’s Emmy Awards at the Shrine Auditorium in Los Angeles-the same huge house where Mr. Letterman executed his memorable Oprah-Uma bellyflop at the 1995 Academy Awards. But though the Emmys don’t have the platinum cachet or viewership of the Oscars-and Mr. O’Brien won’t be trying to please as tough a live audience-his performance will be one of those Big Defining Moments in his on-camera career.

If Mr. O’Brien can strike the proper tone in prime time-that deft combination of roasting and toasting that leaves both celebrities and civilians with elevated endorphin levels-then he will add to the growing consensus that he is presidential material, ready to lead the nation merrily into dreamland at 11 or 11:30 p.m., and not just a gerrymandered district of clever insomniacs at 12:30 a.m.

Mr. O’Brien said that Friends co-star Lisa Kudrow, whom he once dated, “told me, ‘You think of everything as a test.’” In true overachieving Harvard fashion, Mr. O’Brien has tacked on an additional degree of difficulty to this pursuit. In January, he married former advertising executive Liza Powel-not in show business-and made it clear that he is looking forward to starting a family.

This might not seem extraordinary, but the talk-show masters of the past inevitably made a choice between public and personal ambition. Jack Paar married a “nice girl”-as he urged Mr. O’Brien to do in a letter he once wrote to him-but ran The Tonight Show for five years before throwing in the towel. Johnny Carson married four times and ran it for 30 years. Jay Leno has one marriage, no children, and Mr. Letterman, well, whenever he gets to talking about relationships it’s a bit like watching Lon Chaney in Phantom of the Opera : as melancholy as it is compelling.

Frankly, the odds of Mr. O’Brien succeeding on both counts are slim, but it wouldn’t be the first time he triumphed against hopeless odds. You may not remember how nearly disastrous was the scary start of Mr. O’Brien’s late-night television career, but he hasn’t.

“People have asked me sometimes, ‘How did you make the show work, because it was difficult and there were a lot of problems and you didn’t have any experience.’ And I said, ‘When a house is on fire and you’re in it and there’s one way out, you’re going that way …. It’s not heroic or anything, it’s just my ass was on fire and there was one way out. I’m not going to be the answer to the trivia question, ‘Who was the biggest loser in late-night history.’”

Lately, Mr. O’Brien’s been looking like a winner. Late last year, representatives from Fox network approached him to consider moving to their 11 p.m. time slot. Sources in Mr. O’Brien’s camp said Fox was alluding to Letterman/Leno-size money, in the neighborhood of $15 million to $20 million. A Fox spokesman declined to comment. Mr. O’Brien wouldn’t comment on the offer, but said, “The amount of money involved to this day has my agents furious at me, but I’ve never made a show-business decision based on money.”

NBC went right to work hammering out a new deal with its Late Night host whose contract was almost up, but as it was being finalized, CBS, which was renegotiating Mr. Letterman’s contract, called. Mr. O’Brien said his representatives-his manager is Gavin Polone, his agents are Rick Rosen and Ari Emanuel of the Endeavor Agency-were excited, but he was not.

“I didn’t really think that Dave was going to leave CBS,” Mr. O’Brien said in June, a few weeks before Mr. Letterman made similar comments during an interview with Ted Koppel. “These things are like giant 600-ton locomotives that you manage to get going 100 miles an hour. You’ve got to have a really good reason for stopping one, building a track somewhere else, lifting it up with giant winches and then trying to get it going in a different direction. I just couldn’t see the reason.”

Besides, he said, “I was not anxious to be the crowbar that CBS uses to get Dave’s number down.”

Mr. O’Brien said he told his representatives, “Let’s not even get involved.” According to sources in Mr. O’Brien’s camp, Late Night brings in approximately $70 million in revenues for the network, of which a little less than half is profit. The papers reported that Mr. O’Brien increased his salary to $8 million per year, his production company Conaco got commitments from NBC to produce primetime program. The network also struck a deal with Comedy Central to begin airing repeats of Late Night .

I asked Mr. O’Brien if he got everything he wanted.

“There’s supposed to be a statue right where the ice rink is, of me urinating,” he said. “It’s not there. It’s an equestrian statute, only I’m riding Tom Brokaw.”

But when The New York Times ran with a front-page story reporting that Mr. Letterman was talking to ABC, Mr. O’Brien said, “I thought, ‘Did I just a sign a four-year deal to stay at 12:30 when there might have been a real need for an 11:30 guy on CBS?’ And I just went, naah .”

As of Sept. 18, 2002 Mr. O’Brien will have completed 1,636 shows during his nine years and five days at the network. “Dave was here 111¼2 years and did 1,800 shows,” Mr. O’Brien said. “I got so much shit when I started this job that, just for personal reasons-and that’s worth a lot more than money-it would be nice if when this whole thing was said and done, I could say I did it for 13 years and 1900 shows.”

I said that he sounded like he didn’t see himself continuing in the 12:30 a.m. time slot when his current contract expires at the end of 2005.

“I don’t think so,” he said, then recalled a phone call from Mr. Letterman in 1993 when he took over Late Night . Mr. Letterman had called Mr. O’Brien to congratulate him and wish him luck. “He was very nice,” Mr. O’Brien recalled. “And he just said: ‘12:30 on NBC isn’t the greatest job in the world, but it’s the greatest time slot in the world.’

“It’s like optics,” Mr. O’Brien said. “If you can get the perfect distance between two things, you can just hit this perfect sweet spot. And there’s something about 12:30 and there’s something about this network and this building. But at a certain point it’s like a 55-year-old man wearing short shorts.”

Late Night with Conan O’Brien showed its comedy genes from the beginning. Comedy was “oozing from every section of the show,” said one writer who was there, reality and surreality were fused: there were fake guests and Nazis in the audience weeping at Mr. O’Brien’s rendition of “Edelweiss.”

Nine years later, Late Night is much more of a late night talk show with comedy. The Masturbating Bear and the Clutch Cargo episodes are still there, but the comedy sketches are clearly comedy sketches and two years ago, Mr. O’Brien’s sidekick Andy Richter departed, leaving Mr. O’Brien no choice but to fill center stage with…himself.

Generally, he has risen to the occasion. There are still moments when he looks small and a little lost on the set-his speech on Sept. 11 of this year was one of them-but mostly he seems to be in the zone. When Mr. Richter was on the show, Mr. O’Brien sometimes seemed to be muting his wit so his sidekick could have a fair share of the spotlight. Now he’s upped his comic candlepower. He looks sleeker and more confident. He is a little harder, sometimes even a little meaner. He is less the fraternity buddy and more … the star.

“If you put in a tape of me anytime in 1993,” he said, “you’d see somebody trying to remember how to do his job, like ‘I got to do this now.’”

Mr. O’Brien brought up the theory of the reptile brain-what some researchers have labeled the oldest part of the human brain. “Your reptile brain carries on respiration, it keeps your heart beating. It’s the part of your brain that’s on autopilot,” he said. “And I think somewhere around 1996, my reptile brain said: ‘Okay, I’m taking care of breathing, heart rate, releasing certain hormones at certain times and these following talk show rules.’ I don’t even think about them anymore.

“You know, I think the genius of Dave was this reality based comedy. ‘We’re going to go out on the street with a camera and find this guy who is making a falafel or making keys’,” said Mr. O’Brien, but he added, “Everyday life has been something I’ve been trying to hide from since I was born. I’d probably be more closely related to Pee-Wee’s Playhouse than to Johnny Carson, David Letterman, Jay Leno.”

Perhaps, but to the casual viewer, there’s a lot more truth-telling going on in Late Night with Conan O’Brien than in those shows. From Triumph the Insult Comic Dog to the E!-parody of ” Secrets! ” to the Clutch Cargo celebrities from Bill Clinton to Bob Dole to Arnold Schwarzenegger to Saddam Hussein to Yasir Arafat who can’t help telling the truth, the trademark of Mr. O’Brien’s show seems to be a kind of sodium pentathol comedy in which the subjects just can’t keep their their inner truth concealed, no matter how hard they try, the pinnacle of which is, of course, the Masturbating Bear.

Late Night offers a comedy corrective for a culture that is constantly being sucked toward a drainpipe of celebrity bullshit, political punditry and religious hypocrisy. Those are our words, by the way.

Mr. O’Brien put it this way: “I don’t mean to sound pretentious, but a big thing about the Late Night show is we have tried to be really honest about everything.”

Scan the short form of Mr. O’Brien’s childhood and you can see where that comedy has its roots. He grew up the third of six children-Neal, Luke, Kate, Jane, Justin and don’t forget distant cousin Denis Leary-in an upper middle class Catholic home in Brookline, Mass. His father, Thomas, is a microbiologist, his mother, Ruth, a retired lawyer.

“Bill Murray”-he comes from an even larger brood-“once said that he learned how to be funny at his family table when they were having meals,” Mr. O’Brien said. “You know, kids are competitive. And my brothers and sisters are really funny. That was my school for a while.

“My self-deprecating style is earned,” Mr. O’Brien said. “I was insecure. I was not good athlete. I had no hook when I was a kid.”

A straight line can be drawn from the competitive, brutally honest big family to Mr. O’Brien’s decision to eschew the lonely life of a stand-up comic for work in improvisation, with the Groundlings and then, later in the brutally competitive but ultimately team-like writing rooms of Saturday Night Live , The Simpsons and, since 1993, Late Night . And now that he’s the performer, he hasn’t protected himself as a subject.

Last week, he appeared in a sketch, written by Brian Stack and Michael Koman, in which Mr. O’Brien’s thuggish cell-phone brandishing “agent” Ari Palone-a hybrid of Mr. Palone’s and Mr. Emanuel’s names-approached Mr. O’Brien, whom he called “C-Dawg”.

“What’s up, Ari?” Mr. O’Brien asked.

“Your career, my friend! You got a red hot show here on NBC. Plus, this guy’s hosting the Emmys everybody,” the agent said. “You’re on fire, baby! Now get up, you’re quitting the show.”

Mr. O’Brien looked shocked. “I’m not quitting the show. I love it here.”

“You’re like a Sperm Whale in a trout pond,” his agent said. “And I’m here to airlift your fat ass to the ocean. Don’t you want your kids to have everything you never had?

“No!” Mr. O’Brien protested. “They’d be spoiled little monsters.”

“That’s why you’d need an emerald covered robot to teach them values,” the agent said.

Soon, Mr. O’Brien’s agent was on the phone telling the network that his client was not hosting the Emmys, listing “our demands”: “10 million bucks. A beach house in Malibu. And a private jet full of whooores .” When an NBC executive arrived in the studio, the agent whacked him over the head with a brick.

“God. What are you doing?” Mr. O’Brien screamed. “None of the executives are going to talk to me now.”

“They will when I scalp him, Conan,” his agent said, pulling out a giant knife.

Then the president of NBC called and gave Conan everything the agent wanted. “Look, maybe we could get you a little more money and a maybe even a couple of whores,” he said.

By the end of the skit, Mr. O’Brien was congratulating his agent.

“Nice work, A-train,” he said.

The audience laughed and applauded.

“The truth,” said Mr. O’Brien later, “is much funnier than anything else.”

Mr. and Mrs. Conan O’Brien met me at the rented penthouse apartment they live in on the Upper West Side while they looked for a place to buy. Mrs. O’Brien is a willowy, beautiful blonde with smart eyes and a Patricia Duff voice. She wore a white buttondown shirt, jeans that had been cut off at the ankles and bare feet. Her husband wore brown.

The couple seemed a little nervous about this In Style -style intrusion. Nonetheless, they gave me a full tour of the apartment which has spectacular northern views of Riverside Park and the George Washington Bridge. The place was fragrant with fresh lillies, decorated in a modern but homey style. On the wall near the kitchen was a framed black-and-white photo of Robert F. Kennedy standing in the back of a convertible, surrounded by a sea of outstretched hands. Books were everywhere, including a biography of Dalton Trumbo, John Richardson’s Picasso opus and, in the bedroom, a paperback of Laurence Leamer’s biography of Johnny Carson, King of the Night .

Against one wall of the apartment’s main living area stood several examples of Mr. O’Brien’s electric guitar collection, including a Les Paul that had been signed and given to him by the man himself. Mr. O’Brien’s obsession with guitars bumps up against his obsession with the Beatles. He owns a limited edition replica of the Epiphone Casino guitar that John Lennon played on Let It Be . He said the guitar was manufactured by the Lennon Estate and is exact down “to the misplaced screw holes, scratches, pick ups and everything.”

“It’s kind of wrong,” Mr. O’Brien said, a little sheepishly. Actually “fucking sick” is what Elvis Costello said when he told him about the guitar.

The couple showed off what Mr. O’Brien called it his “chamber of delusions.”

A spare room, outfitted with Liza’s computer-she is currently writing short stories and working toward her M.F.A. at Columbia University-more guitars and a wall of framed clippings and photos all pertaining to Mr. O’Brien.

“I don’t have a lot of show business memorabilia around the house, but then I concentrated it all on one room,” he said. “And that’s got the picture of me and Johnny. And a shot of me and Dave from the monologue mark. And a letter from Jack Paar.”

Liza Powel O’Brien sat in a chair across from her husband. She met him in Spring 2000 when, for a show segment, he had enlisted a group of creative executives at an ad agency to produce a commercial for a Houston furniture salesman who was advertising in the show even though it was airing at the ungodly hour of 2 a.m. After participating in the part of the shoot that took place at Ms. Powel’s agency, Mr. O’Brien said he told the show’s head writer, Mike Sweeney to “make sure you get everyone’s address and phone number.”

Mr. Sweeney said, “It’s the blonde, isn’t it?”

After several weeks of flirtation on the telephone, he invited Ms. Powel to have coffee at a restaurant in her Upper West Side neighborhood on an April Saturday afternoon. As he waited for her to arrive, he said, “I was hoping that it would be, ‘Oh yeah, she’s not the way I remembered her looking.’ And ‘this is disappointing somehow.’”

But when Ms. Powell walked in, “the first thing I thought,” he said, “was, ‘Oh shit,’ It’s very hard to explain, but I just knew. I was, like, ‘There goes my cool ‘one of People magazine’s 50 Most Eligible Baaaaa-” He never finished the word, letting it wave off into a Lou Costello-esque stammer.

Mr. O’Brien smiled.

“When you meet that person, you can’t say, ‘I’m not ready-I need to be with a few alcoholic supermodels with rage issues,’” he said. “I think I’m fortunate in that there’s something inside me that usually makes me do the thing that’s best for me to do. I think I’m the opposite of a self-destructive personality.”

Soon he found himself facing a big decision.

“Of course the next question is, Do you think that you can do the kind of show that you do and still have a happy marriage and family life? But I didn’t even need to ask it.”

Conan O’Brien sat up straight.

“I came to the conclusion that that’s bullshit. That plenty of people are just amazing at their jobs and also manage to have a pretty good relationship with somebody else and have some kids that aren’t too fucked up.

“I’ll accept that if you’re painting the Sistine Chapel, I’ll accept it if you’re the great poet of our time. But when someone’s like-‘No! In order to do my chat show, I must be alone,’ I think, ‘Wow. That’s like saying, in order to make this cotton candy store run efficiently, I must never marry and I must never have children.’

“I’m betting that I can do both,” Mr. O’Brien said. “That’s my bet.”

Liza Powel O’Brien called her husband a “highly connected person” who “likes to discuss things and likes to analyze things” and who has “retained his niceness, which I think is hard to do even just living in New York City.”

She also said that he sometimes has the thought that “comedians are all really kind of fucked-up bitter people and if I have an O.K. life and I’m pretty happy, is that going to hurt me? I think that’s sort of like saying you have to be drunk to be a good writer. Yeah, they go hand in hand, but they’re not necessarily linked.”

Conan O’Brien sat uncomfortably in a booth at an Italian restaurant on the Upper West Side. He had finished his lasagna Bolognese and had moved on to coffee.

He said that he has been in and out of therapy since the late 1980’s when he was at Saturday Night Live and found that his whole self-worth was wrapped up “in whether I had a good sketch or not.” His search to better understand the dark moods that occasionally envelop him-and, it’s safe to say, a great deal of creative people-has clearly been important to him and, though he said he used to be reluctant to discuss it, he spoke quite freely about it during his interviews with the Observer .

He explained that his talent for coming up with weird, funny images quickly makes it equally easy for him to imagine extreme, depressing thoughts that are just as vivid as the funny ones. “I can make negative connections, like, huh, the crowd was a little quiet tonight. I think those people weren’t really into me. I think the best years are behind. I think I’m going to die. Alone.”

Mr. O’Brien’s therapy of choice is the common sensical cognitive brand that focuses on how the mind works like “circuit board” and what are “destructive” and “constructive thought patterns.” He added that he wasn’t interested in the kind of therapy where “I close my eyes and talk about how I had this dream of buttering my Dad’s ass with a turkey baster. Let me tell you something,” he said. “That dream’s nobody’s business.

“There’s no cure for getting depressed. There’s no cure for self-loathing or periods of it,” he said. “But figure out enough about it so that when it happens, you can get over it and keep moving and just accomplish more.”

Mr. O’Brien’s psychotherapeutic education has not changed his mind about comedy’s inextricable link to the darker side of the human mind. “I think that whether you want to admit it or not, anxiety, self-doubt, a pinch of self-hate, some cayenne pepper, that is the ingredient for doing good work,” he said. “The sad part is I do believe it’s fuel for comedy,” he said. “The consolation prize for people who had some depression and didn’t quite fit in in school, our consolation prize is we get to be comedians. That’s the gift that we get. That’s just how it works.

“I’m always going to be a little bit depressive and obsessive-compulsive about this stuff that I do,” Mr. O’Brien said. “But I don’t want to take it to the point where it actually starts to hurt the work. I think there are times where it’s not the fuel anymore. It’s like a bell curve. A parabola.” Mr. O’Brien put his hands together like they were a needle on some kind of psychographic measurement device: “The Depression’s helping. The Depression’s helping,” he said as he moved his hands to his right. “Whoa! It’s not helping anymore.”

Mr. O’Brien called himself “a work in progress” on the subject of understanding himself. “I’m not cool now. I’m not,” he said. Oh Jesus no.” But things are better. “What used to freak me out,” he said, “is in 1994, I’d go see a therapist and I’d say, I think people think I’m a fraud and that I’m no good at what I do. And the therapist would say, ‘Trust me, that’s a voice in your head. It’s not reality. It’s not what anybody thinks.’ And I’d say, ‘Really? Then how come it says so in USA Today ?” His eyes crinkled and he began to laugh.

“I actually enjoyed that,” Conan O’Brien said. “Not many people can produce clippings that back up their paranoid fantasies.”

Then a woman who sounded and looked a bit like Cindy Adams approached the booth.

“Excuse me, God will strike me dead for talking to you, but you really make me laugh.”

“Oh that’s nice,” Mr. O’Brien said.

“You are one of the funniest people, I-excuse me, I shouldn’t. God will strike me dead for saying this…”

“No, he won’t,” Mr. O’Brien said.

“But you really are funny.”

“Yeah, God’s going to be mad that you complimented me!” Mr. O’Brien said. And when the woman walked away, he leaned in and whispered. “See? And I’m like, `Why would God strike you dead? What’s so bad about liking me?’” Mr. O’Brien waited a beat. “You know what’s sad?” he said. “She thinks I’m Ted Koppel.”