A friend took me to see the last preview of “South Pacific” before it opens tonight at Lincoln Center. I was excited to see this monument of the American Musical theater for the first time. To my amazement it turned out to be about race, when I always thought it was about hygiene.

In Paris as a child, all I knew about the show was that American friends of my parents’ would get tipsy and sing: “I’m gonna wash that man right out of my hair!” It was clear that we Americans washed our hair more often than French people; I assumed it was because we were cheery and innocent, like the slightly doughy looking Mary Martin on the cover of Original Cast Recording that my parents lugged around Europe as a touchstone of their home country.

To me, the shock last night was the story: I had never seen the film. The set of the Lincoln Center production, backed with a giant map of the islands of the South Pacific, suggests the vast tragedies of war. I was surprised that the show begins with two children singing, in French, the same song my grandmother used to sing to me: “Dites Moi, pourquoi, la vie est belle (Tell me why life is beautiful).” So, that’s where she got it!

I was more surprised to see that despite soldiers and sailors and marines and large engineered things and flashing lights and references to jeeps, “South Pacific” is about the love between a young woman from Little Rock and a French island dweller. And what comes between Nellie Forbush and Emile De Becque is not war, but Nellie’s horror at the revelation that Emile’s children are half Polynesian, because he was married to a woman … of color!

The presentation of race as an impediment to love is underscored by the subplot, wherein Lieutenant Joseph Cable, a Princeton graduate (read: an aristocrat ), falls in love with Liat, the daughter of the Tonkinese skull peddler Bloody Mary. In the manner of subplots, Joe and Liat have a tougher time than Nellie and Emile, but there are Enchanted Evenings again and again.

The spine of the story set me thinking about the importance of class and race in so many works of musical theater. As if, in fact, musical theater relied on the tensions of race and class for its plots: In “Madame Butterfly,” the Japanese Cio Cio San bears a child to Pinkerton, but since he marries a white woman instead, all she can do is kill herself. In “La Traviata,” Violetta and Alfredo are in love, but she is a courtesan, so his father convinces her to leave Alfredo, thereby causing Violetta to die of a broken heart as well as tuberculosis. In Jerome Kern’s 1936 “Showboat,” the plot revolves around the sheriff’s declaration: “One drop of Negro blood makes you a Negro in these parts.” Even in “West Side Story,” the enemy clans are the American (white) Jets and the Puerto Rican Sharks, which has a little more edge to it than the uniformly Veronese Montagus and Capulets. And Bob Fosse’s 1972 “Cabaret,” set in Berlin in the 1930s, had the song: “If you could see her like I do .. she wouldn’t look Jewish at all.”

I can actually write about this because I am a Jew with, if the DNA test is to be believed, 4 percent African blood and 12 percent East Asian blood. If I could not claim black and Asian ancestry, the mere typing of the words Color, Negro and Jew would label me a racist. We are in a period of aggravated political correctness where the naming of any difference between peoples violates the rules. There’s an ugly assumption behind these rules: that racism is so prevalent in the human psyche that people need border fences to keep it out of sight.

But differences between people are the basis of conflict, thus drama, thus tragedy. Which brings me to wonder if that is not the reason why there is so much mechanical, blind, pointless violence in films and television today — an undifferentiated threat to which no one can take exception.