We all know the wonderful score of Rodgers & Hammerstein’s South Pacific. The romantic ballads such as “Some Enchanted Evening” and “Younger Than Springtime,” the joyous numbers “Cock-Eyed Optimist” and “In Love with a Wonderful Guy,” the humorous songs “Nothing Like a Dame” and “Honey Bun,” and the insightful lyrics of “You Have to Be Carefully Taught” – these all play in our heads.

Many of us saw the movie, but none of that familiarity prepares you for the pure jolt of emotion that the performers in Lincoln Center Theater’s production of the musical South Pacific, as directed by Bartlett Sher, sends out to the audience. While being utterly true to the original intent of the show, Kelli O’Hara as Ensign Nellie Forbush, Paulo Szot as French planter Emile de Becque, Matthew Morrison as Marine Lt. Joseph Cable and a cast the New York Times calls “flawless” reveal levels and nuance that take your breath away.

“Even when crying, the audience is happy,” Julia Judge, Artistic Administrator of Lincoln Center Theater, said of the feedback she’s gotten from theatergoers. Ben Brantley in his New York Times review wrote, “I could feel the people around me leaning in toward the stage as if it were a source of warmth . . . it’s the fire of daily life with all its crosscurrents and ambiguities underscored and clarified by music.”

I saw South Pacific on Memorial Day weekend when Fleet Week filled New York with sailors and marines who are serving in Iraq and Afghanistan. When Lt. Joe Cable jumps out of the airplane that brought him from combat on one of the islands on which the marines fought so fiercely and lost so many, we’re with the characters at every turn. South Pacific seems to speak directly to us today. It’s our story as Americans that’s up there on the stage.

And here is Nellie Forbush (O’Hara) singing, “I heard the human race is falling on its face, and hasn’t very far to go. But every whippoorwill is selling me a bill, and telling me it just ain’t so.” That’s the spirit that animates South Pacific. And O’Hara, who was nominated for Tony awards for her roles in The Light in the Piazza and The Pajama Game, and this year for South Pacific, is an actress who can thrill us with her voice, astonish us with her dancing, amuse us with her clowning and still reveal a woman who comes to question all her unconscious beliefs.

I met up with O’Hara one evening in early August. She talked about her family history and heritage when I sat down with her in her dressing room prior to another sold-out Friday night performance.

“I’m proud to be Irish,” she said, though she grew up far from the usual Irish-American centers. “I was born and raised in Oklahoma. Both sides of my family came there during the time of the land run in 1889. [The land run started at high noon on April 22, 1889, with 50,000 people dashing for their piece of the two million acres opened for settlement.] My great-grandfather, Peter O’Hara, was born in Ireland, I believe in County Clare. His father, my great-great-grandfather, had actually come to America a generation before when times were very bad in Ireland. He worked in the Pennsylvania area and did well with horses and farming.

My great-aunt, who is in her nineties, told me the story. She said that he went back to Ireland, either to get his family or to live there with his newfound wealth, but he was actually forced to leave. Something happened and he had to take his family and nothing else and escape at night. This would be at the end of the 19th century. Three of his sons, my great-grandfather Peter and his brothers James and Michael, split off from the rest of the family to go find land. They landed in western Oklahoma and participated in the land rush. We still farm the land that they found. My dad’s brother Robert lives on the original farm. My father and brother are both Patrick O’Haras. Our family has a long wonderful history of Irish lineage that I’ve enjoyed learning about, though I don’t know enough. “It’s sad how the stories get lost. I want to write down my great-aunt’s memories. We do have one precious possession that’s been handed down. It’s an Irish cookbook that we use all the time. On the cover, written in Irish, is O’hEaghra : O’Hara.”

A cookbook. That’s different. More often it’s Irish music.

By my time, we had only a song or two, and every once in a while an aunt would pull out an Irish blessing and read it. But the biggest thing for us is food. Corned beef and cabbage—that’s our favorite holiday meal when all the O’Haras gather around the table.

So it was a way for everyone to remain connected to Ireland. Yes. My father named me Kelli because “Kelli O’Hara” just sounded so Irish. Even growing up in the middle of America, I felt grounded because I had such strong roots. We were living in the town where my grandfather had grown up. There were a lot of O’Haras from those three sons, James and Peter and Michael–many, many cousins.

Tell me about your hometown.

Elk City is in western Oklahoma near the Texas panhandle and both my parents grew up there. We’ve had our land since 1889. We just celebrated the centennial of our statehood in 2007, an event that Rodgers & Hammerstein celebrated in Oklahoma. Life is a strange bit of circles, isn’t it? We didn’t have much formal theater. My dad was a farmer. He went back to school and he’s now an attorney. My mom is a teacher. There was singing in church and at weddings. We were Catholics in the Baptist Bible Belt. Our church, St. Matthew’s Catholic, was central to our lives. I grew up singing in church and I loved it. I went to Oklahoma City University where my teacher, Florence Birdwell, helped me think outside the box. When I graduated, I could have gone on to grad school or studied more music, but I eventually found myself packing two suitcases with no clue and moving to New York City ten years ago. I think it scared my parents a lot, but they put me on that plane. I just had a feeling that if I didn’t try I would never forgive myself. Somehow I wasn’t even afraid. But then, look at my great-great-grandfather and all the Irish who headed out into the unknown. When I read Frank McCourt’s Angela’s Ashes, I thought, I know these people. I understand their humor, their endurance, their strength.

And now after your great successes in The Light in the Piazza and The Pajama Game, you have made Ensign Nellie Forbush come to life. Could you talk about that process? I find everything through personal connections. I have pictures in my dressing room of my grandmother on my mom’s side, who was English. She was from right outside Little Rock, Arkansas. She was blond. She was feisty. She grew up in the time before civil rights, when children were “carefully taught,” as the song says. She was the person in my head when I started thinking about Nellie. When you go to acting school, everyone wants you to say what your big problems are so you can weep. But I’m not going to lie about the fact that I had a good childhood. I had two sets of grandparents in my little tiny town and I walked barefoot down the street and everyone knew whose daughter I was. I’m proud of that and I’m using it. I suppose there are a lot of reasons to be jaded or sarcastic or bitter in life. But I hang on to the reasons why life is beautiful. It helps to have a history to think about, to remember those who came before you, to help you be in this place. I feel very fortunate. I don’t feel held down, or that I need to create angst in order to be a good artist. I feel like my artistry comes from the things I do believe in. I’m very happy. The longer I play Nellie Forbush, this cock-eyed optimist person, the better I feel about that.

And Nellie was also a professional woman, a nurse, liberated for her time. But liberated doesn’t mean that you don’t fall in love and that you don’t lose control of all sense of anything. It’s something I’ve struggled with before, to find that openness. But once you allow it to happen and you really believe in it, then, gosh, nothing feels better. When you actually allow yourself to just be grateful. I feel that way especially since I married my husband, Greg Naughton, a year ago. He’s an actor and a singer and has a wonderful theatrical heritage from his father, James Naughton. And he’s Irish. My father-in-law’s mother had passed on before I came into the picture, but Greg said, “She would have loved you just because of your name.” We met through a mutual friend and just kind of immediately hit it off. I felt like I knew him somewhere before. Maybe somewhere back in Ireland, something aligned. He’s a great person. We’re happy. He’s been very encouraging to me and was instrumental in helping me with my new CD Wonder in the World that I did with Harry Connick, Jr. Our kids will need a lot of sunscreen, though.

Are there other new things you are working on? I’ve been working on a new musical, just in workshop, called Writing Arthur [composer-lyricist-librettist David Austin’s musical – about an agoraphobic bookshop clerk/novelist] which is set in Dublin but in a dream. It’s about an American man who is writing a story about this tiny village, kind of like Brigadoon. It’s modern-day, but in his story everything is magical in this little place. I play Alanna, which comes from the Irish, “my dear child.”

Have you ever traveled in Ireland? It’s my biggest goal to visit there, especially with Greg. I did spend a night in Ireland one time. It was the most surreal experience, because I’ve always wanted to see the countryside of Ireland. I was coming from London and it was winter and there was a storm here in New York City that kept the plane from crossing the Atlantic. We were diverted to Shannon Airport. It was kind of a scary moment – they took us to this hotel in the middle of nowhere. It was dark, late at night. It was about two years ago. I sat with several Irish couples and they told me about Ireland and how they grew up. They were about my own age. I had a pint and went to bed. And when I woke up, I looked out the window and I was in the middle of the Irish countryside. There were rock walls and sheep and rolling green hills. It seemed unreal because it was so what I’ve imagined. You know, when you go to a country and imagine what it will be but it’s not, it’s just like New York City? Well, this was as I’d imagined. Then they took us back on a bus and I flew away. It was almost like I’d been magically transported to an essential version of Ireland. Later I found out that I’d been looking out at the hills of County Clare where the O’Haras are from. I couldn’t wait to tell my parents, my brother Patrick, and my sister Anne Marie. I’m very proud of my family.

I’m sure they’re proud of you. Well, they’ve been up here four times to see the show! I’m just so grateful to be involved with something that says something about this world.