Nichols’s films seem to speak for their time—“The Graduate,” “Carnal Knowledge”—and sometimes uncannily so. “Primary Colors,” about a presidential candidate of voracious appetites, opened just after the Monica Lewinsky scandal broke. Though “Charlie Wilson’s War,” based on the nonfiction best seller by George Crile, is set in the 1980s, its themes—Washington power-brokering, and the secret arming of Afghan rebels against the Soviets—hit home in the post-9/11 world. But politics isn’t Nichols’s motivation. He’s after singular characters he can unpeel in front of the camera.

At first, he resisted taking on “Charlie Wilson’s War.” “I don’t like reality movies,” he says. “You can’t make anything up.” Then he met the real Charlie Wilson. “Here was a politician who was not prerecorded,” Nichols says. “He’s not simple at all.” Wilson is a good ole boy of immense, unpredictable charm (he even briefly dated Nichols’s future wife, Diane Sawyer), and Aaron Sorkin’s knowing script plays up the comic possibilities of Wilson and the quirky figures surrounding him. The film begins with a richly detailed sequence of scenes—a Las Vegas hotel, a Capitol Hill office—each a perfect little playlet that shows off the director at his best.

Nichols, a youthful-looking 76, is at an age when most directors would be polishing their trophies—and he has plenty, including Tonys (most recently for “Spamalot”), Emmys (“Wit,” “Angels in America”) and an Oscar (for “The Graduate”). But living in the moment, he says, “is the only way I know to try to control the maelstrom in which we sit. I mean, the two things that matter most to me are love and work.” He is sitting in an old Eames lounge chair in his office, high above Broadway, among pictures of his children (three, now grown, from earlier marriages) and of his wife. Love and work are “forever intertwined,” he says, “starting with Elaine.”

That would be Elaine May, his best friend and frequent collaborator, with whom he began performing improv in Chicago in the 1950s. They were a pair of brilliant misfits. Nichols, born in Berlin, the son of a Russian-Jewish doctor, had come with his family to America to escape the Nazis when he was 6, and he always felt like an outsider. But Nichols and May were a smash, bringing their urbane act to New York and recording albums that became fixtures in a certain kind of 1960s American household, along with a subscription to The New Yorker. One LP cover shows a boyish Nichols with a winning grin—an image Norman Mailer dubbed “the royal baby.” People also started calling Nichols—“to my horror,” he says—Mr. Success. By the time he was 36, he’d directed his first Broadway play, Neil Simon’s “Barefoot in the Park,” made his first movie, “Who’s Afraid of Virginia Woolf?” with the two biggest stars of the day, Elizabeth Taylor and Richard Burton, and won an Oscar for his second movie.

Forty years later, Nichols is still living down his wunderkind résumé. He’s had what he calls some “hilarious failures”—“The Day of the Dolphin,” “What Planet Are You From?"—and some bombs he didn’t see coming—“Wolf” with Jack Nicholson and “Regarding Henry” with Harrison Ford. After critics panned “The Fortune” in 1975, he stopped making movies for seven years, though he refuses to call that a “slump.” “Of course, I’ve had slumps in my work,” he says, “but at that time, I just couldn’t find a movie I wanted to do.” He came back with “Silkwood”—one of his finest films, filled with deep purpose and stunning performances, including Meryl Streep’s in her first of several roles for Nichols.

Yet what seems to bug Nichols’s critics is that many of his films don’t measure up to his reputation for genius: they’re accessible, even shamelessly entertaining (“Working Girl,” “The Birdcage”). “If you want to be immortal,” Nichols says, “stick to one kind of movie. Be the master of suspense. Be our greatest comedian to cause warm laughter. And then all the guys in France with cigarette ashes all over them can make their lists, and the bloggers can write each other about arcana. I say, do something you want to do, as well as you can—who cares if you’re immortal?”

Whatever he’s doing, Nichols still looks over his shoulder to his beginnings in improv. “There’s very little that’s better to teach you what makes a scene,” he says. “First and foremost is a fight—a fight is a scene. And then, Elaine used to say, if all else fails, seduce. It works in life, too, but that’s another story.” At the heart of those scenes are the characters. “We might do some visual experiments, but then he would change his mind and say, ‘Nah’,” says Stephen Goldblatt, the cinematographer on “Charlie Wilson’s War.” “What he meant was that it didn’t show Charlie Wilson’s character.”

That focus on character has won Nichols the devotion of actors. In rehearsal, “he talks about the state of the world and the human condition,” says Emma Thompson, a star of “Primary Colors” and “Wit.” He doesn’t instruct but suggests a human quality or impulse. What Nichols loves about movies is that “a lot of people are sitting in the dark sharing something that can’t be put into words. And since all of life is basically not mentioning the main thing—that we’re going to die—we’re used to the idea of something bigger than anything going on but unspoken.”

If that sounds glum—if Nichols is, as the critic John Lahr wrote, “fundamentally inconsolable”—it’s an occupational hazard of the artist. Yet Nichols, who spent years giving his unconscious a workout, hasn’t been in analysis for decades and seems—dare we say?—happy. “I feel like I’ve been almost unbelievably lucky—lucky that all the awful stuff was in the beginning of my life. Whatever it did to me, it didn’t take too much away.” He’s been happily married to Sawyer for almost 20 years—“there are no words to use except to say it is never anything but surprising and sustaining”—he loves his kids, he has serious money and a vast circle of friends. “He’s met practically everybody from God to Muhammad Ali,” says Thompson. Then there’s work. This spring, he’ll stage a Broadway revival of “The Country Girl.” And Elaine May is writing a “small movie” about Jerusalem that he’ll direct: “It’s a comedy about reconciliation,” he says.

Nichols once figured out there were only two movies that “tell us pretty much what movies are.” One was “The Wizard of Oz”: “I saw it with my dad when we first got to this country.” Much later, he realized that it was the story of all searches for knowledge—full of adventure and peril. The other was “Casablanca”—“though I’m hilariously aware of its flaws,” says Nichols—with its story of giving up what you love for something more important. We know where Nichols’s latest movie fits. “The main thing about Charlie and what his story expresses is that a person can make a difference,” he says. Wilson, a cheerful libertine who’d done almost nothing in Congress, has his heart touched by Afghan refugees and decides to take action. As in “Casablanca,” Charlie loses the girl—his Houston socialite—but gains an unlikely buddy—Gust, a maverick CIA spook. But Charlie’s no Bogart. He’s too paradoxical, too funny and far too flawed. In other words, a perfect Nichols hero.