Happy birthday, Alan Alda.

"Today's my birthday," the actor says, savoring the thought through a squint-eyed Hawkeye grin. "Yeah. I love it."

Actually this is not his World Almanac/Who's Who/government-certified birthday -- that comes in January -- but the one he has chosen for himself. Two years ago on this October day, a doctor in La Serena, Chile, performed emergency surgery on an intestinal blockage, saving his life and, the actor says, altering his worldview in wondrous ways. On his return home, he embarked on a frantic writing jag that eventually produced a memoir, "Never Have Your Dog Stuffed," which has arrived in bookstores to warm reviews and brisk sales.

For Alda, 69, the bestseller's publication extends and expands a gaudy winning streak in his acting career; 2005 has brought him Oscar, Tony and Emmy nominations for "The Aviator," "Glengarry Glen Ross" and "The West Wing," respectively (and tonight, his "West Wing" character, a GOP senator, will square off in a live presidential debate with Democratic Rep. Matthew Santos, played by Jimmy Smits). If this is Alda's Day of Days, it's also his Year of Years.

But the book is clearly a particular delight for him, at least partly because he never set out to write one.

"I don't know what I was trying to achieve," he says, settling into a booth at a West Side Italian restaurant. (He and Arlene, his wife of 48 years, live in the city, and any time his "West Wing" and book-promotion schedules allow it, he's here.) "I was in a hypomanic state. I just couldn't stop writing. . . . I was writing about -- I guess up to then the most important thing that had ever happened to me, being given my life back. And I just couldn't get over that. I was amazed at that."

Initially, his writing focused on the near-death experience, and he hoped to have it published as an article. That proved a hard sell, but his friend Charles Grodin showed the work to his editor at Random House, who suggested that the star of Broadway, film and, most famously, television's "M*A*S*H" had a book in him. The result, as its title suggests, is not a comprehensive autobiography, but neither is it a showbiz potpourri of notable names, famous feuds and annotated triumphs. (The title is a reference to his childhood cocker spaniel, Rhapsody, who died after eating Chinese food. So heartbroken was the boy that his father suggested having the dog stuffed -- "That way you could always keep him" -- which turned out to be a lousy idea.)

"I didn't want to write an illustrated resume," he says, "and I didn't want to write 'My Life in Bed.' "

The book is very much the tale of Alda's inner life, and a goodly chunk of it is devoted to his troubled childhood. His mother, a paranoid schizophrenic and an alcoholic, tormented his father, actor Robert Alda -- they ultimately divorced -- and caused her son to take on a strong early sense of detachment.

But beyond that, the young Allie -- he was born Alphonso D'Abruzzo -- is most notable for his raging curiosity. "I've carried that through all my life," he says. "From the time -- I remember in my twenties when I was riding in elevators a lot, going up to people's offices, either to sell myself or sell them something else as a part-time job, I'd be standing in the elevator, and on the ride up . . . I'd look at the panel of buttons, and I'd wonder how it got that way. Who put it in, how did they do it, why was it designed that way? Not because I needed to know the answer for any reason, but I was curious."

He smiles. "It interests me that I still think of myself as a kid."

Alda knew from an early age that he wanted to be an actor. His father began in burlesque, became a featured player at Warner Bros. and played Sky Masterson in the original "Guys and Dolls," all of which guaranteed the aspiring performer some measure of access. But as his recollections make clear, the younger Alda's progress was slowed by a nearly complete lack of training.

"I had problems with that," he says. "I had to learn how to be taught. I had to learn how to learn. It's very easy to think you know everything, especially if you've had the background I had. I was very self-centered. I also didn't trust people."

He's speaking of his mid-'50s self, who sounds like a medium-size pain. But it was during this time that he met Arlene, and he trusted her right away. "I wanted to be married and have a family," he says simply. "I always wanted that." The two were married in 1957, and for years theirs has been a much-admired union. "People always make a big deal out of it," he says, sounding perplexed, "as though it's unusual for people who work in Hollywood to be married a long time and be happy. But the interesting thing is, most of our close friends have been married 40, 50, 60 years. And I'm talking about close friends who also work out there."

Arlene was an accomplished clarinetist, and at the time of their marriage, she'd been hired by Leopold Stokowski to play with the Houston Symphony Orchestra.

"She was the one who was working," he says, "and we moved to New York so I could be out of work."

The marriage produced three daughters -- Eve, Elizabeth and Beatrice -- and the family settled in New Jersey. By the mid-'60s, Alda had made a name on Broadway, with successful engagements in "The Owl and the Pussycat" and "The Apple Tree." That expanded into a nice mid-level movie career, which was interrupted in 1972 by the offer to play Capt. Benjamin Franklin "Hawkeye" Pierce on "M*A*S*H." The show became so successful -- the 1983 finale remains the most watched entertainment program in television history -- that it's easy to forget that in some quarters, its initial prospects were considered rather dim.

"Nobody knew," he says. "Even the studio -- you know? -- they put us in the smallest soundstage because they didn't think it would work."

The series gave him the opportunity to try his hand at directing and writing, and he won Emmys for both, as well as for acting, a rare distinction.

Alda evinces a special reverence for writing; one of the book's few Hollywood touches is the scene of him turning a cartwheel on the way to the podium to accept a writing trophy.

The book's remembrances of the show's 11-year run are personal and positive -- and rather brief. Most of his fellow players are given an affectionate sentence or two. There are allusions to certain conflicts on the set: "And, often, we stayed in the chairs long after we had finished the shooting day to listen to one another's heartfelt, sometimes bitter gripes and looked for compromises. But mostly, we made one another laugh." Whatever the fights were about, it's the reconciliations he wants to remember.

"M*A*S*H" reruns have never left us, and Alda knows the show remains the foundation of his fame. It was during the show's original run that he began to be referred to as the Ideal Man -- caring, tender, sensitive, perfect husband, peerless father -- a 1970s icon.

Remember?

"Well, sure," he says. "Because they kept writing that. It was embarrassing. I didn't know where it came from. But on the other hand, you read something like that -- well, it's better than saying I'm an armed robber or something, a dope fiend. But I always would have been more comfortable if I had been seen as a three-dimensional person."

All that admiration had to carry a consequence, and ultimately Alda faced a backlash.

"You get things said about you that, if a person came over and said it to your face and you weren't famous, you'd say, 'Why is this person treating me like this?' But they feel totally free to do this to famous people. Because you're famous and you're not you anymore. You're not a person. You're a cartoon character. . . . Maybe you deserve to be knocked down a peg. Who the hell are you to be famous?" He smiles. "Well, which is true. But on the other hand, somebody's gotta do it."

Alda's "West Wing" character, Sen. Arnold Vinick, is running for president this season as the administration of Martin Sheen's Josiah Bartlet comes to a close. So even though nobody on the show is talking, you have to ask --

"Who's gonna win?" he says.

Yeah. Who's gonna win?

"They actually -- the producers, I've heard from other people, mutual friends, they're actually saying to their friends that they don't know who's going to win. So I think that's a really good misinformation effort." He laughs.

"West Wing" Executive Producer John Wells has hired Alda twice ("I wish I could use him about 30 more times"), the first time being for an "ER" story arc involving a doctor with Alzheimer's disease.

"He's an extraordinarily talented actor and sort of universally likable," Wells says, "and you can play on all the complexity beneath the surface. You can play on people's assumptions about him. He's also remarkably professional and wonderful to work with. He infuses the cast with his sense of dedication and professionalism."

Wells says that within a month or so, the creators will be ready to shoot the election night episode, which should air the first or second week in March.

"Somebody has to lose," he says. "We've been having so much fun doing what we're doing that we all kind of dread it."

Alda says he's really looking forward to tonight's debate. With his background -- he did a lot of improvisation in his early days -- he seems perfectly suited to the live format.

"Well, only in the sense that I won't be -- I don't think I'll be too nervous about it being live. But we're going to be prepared. I mean, real presidential debates are scripted, of course."

In a telephone news conference three weeks ago to announce the live broadcast, Smits appeared to be seeking to lower expectations, announcing more than once that "Jimmy is not a good talker."

Long laugh. "I hadn't looked at it that way," Alda says. "Of course that's what he was doing. Yeah, that's right -- 'Jimmy's not a good talker.' Yeah. Okay, well, what I'll do is raise expectations and then come in under the radar. I know that doesn't make sense, but I'm thinking laterally."

Clearly, Alda has his own way of thinking. When he was stricken in Chile, he was completing an installment of PBS's "Scientific American Frontiers," which he hosted for 11 years. The surgeon explained to him what had happened -- the blood supply to his small intestine had become choked off and the tissue was dying -- and said he had to remove the bad part and sew the good parts together.

Alda, then Andes-high on morphine, said, "Oh, you're going to do an end-to-end anastomosis."

"How did you know that?"

"I did many of them on 'M*A*S*H.' "

The doctor laughed. Alda writes: "Through my haze, I smiled. My real illness, it seems, is my compulsion to amuse. Apparently, you can offer to disembowel me, but I'll still see if I can make you laugh."

Call it his illness or simply his MO. The talent -- and the will -- to amuse has given Alan Alda lifetime passage through the world. He's clearly pleased with himself, but then he has a lot to be pleased about.

And does this very pleased man have a proudest achievement?

"I think it's the book," he says quickly. "Because I've been trying to be as good a writer as I can since I was 8 years old. And that's a long time. That's 61 years. . . . I hope 10 years from now I would be able to write a better book. But I'm very happy with this one -- I only hope I can write a better one because I want to keep getting better."

Alda might or might not be chosen as "West Wing's" new president, but he's keenly aware that he's living a special time. His 70th birthday will fall in the middle of the shooting schedule -- "We'll probably go out to dinner or something" -- and book promotion and the series will consume him until at least March. It all sounds heavy and high-pressured, but then it's a special thing to be in demand.

"This has been -- I mean, since I was born again, two years ago today, this has been absolutely wonderful," he says. "I've been extremely busy the whole time, and amazed and happy, more than I've ever been in my whole professional life. . . . I wasn't amazed when I was working hard in my thirties and forties. It just seemed like the next step, you know? I should have been amazed, because it was an amazing success I had. But I was so busy doing it that I wasn't amazed."

Big crinkly grin. "It's fun to be amazed."

Alan Alda, two years past a life-saving operation, says he's "amazed" by his continued good fortune. Tonight, his "West Wing" character participates in a live presidential debate. He's also published a memoir, "Never Have Your Dog Stuffed."Alan Alda. left, on Broadway this year in "Glengarry Glen Ross" (with Liev Schreiber), which garnered him a Tony nomination.On "The West Wing," Alda's Sen. Arnold Vinick is running for president against Jimmy Smits's Rep. Matthew Santos.