Happy About That Lovely Sad Jazz : The blues has slipped inside the Performing Arts Center’s back door. Now it’s time for the big stage.

What is “the blues”? Depends on whom you ask.

Webster’s defines the blues as: “Black folk music characterized by minor harmonies, typically slow tempo, and melancholy words.”

The folks at the Orange County Performing Arts Center, who sponsored several performances last week by blues musicians John Cephas and Phil Wiggins as part of the Imagination Celebration for children, were (predictably) higher of brow:

Quoting from the Encyclopaedia Brittanica, the Center’s program told of “Afro-American vocal and instrumental style, characterized by expressive pitch inflections (blue notes), unique tone qualities, a text-phrase construction based on a three-line stanza and, typically, a 12-measure form.”

What--no iambic pentameter?

The program writer went on to add that in the blues, “African influences are apparent in the call-and-response pattern, the falsetto break, the blue tonality and the imitation of vocal idioms by instruments. The blues contribution to music is immense, as it has been a major influence on all forms of jazz, as well as contemporary popular and rock music.”

Got that?

For 13-year-old Eva MacGillivray of Irvine, though, it took just two words to define the blues: “It’s sad jazz .”

Eva and three girlfriends from Irvine were at the Center on Monday night as guitarist Cephas and mouth harpist Wiggins, both from Washington, presented “Chewing the Blues,” a touring concert-cum-play designed as a blues primer.

Walking into the Center’s small Founders Hall theater, the four girls didn’t know much aboutthe blues--exactly the sort of people the program was designed for. Twelve-year-old Gusti Lind’s mother, Shirley, brought the girls because, she said, “I think it is important that children be exposed to different kinds of arts and culture.”

When Eva heard that, she rolled her eyes and said, “That’s what my mom says. Do you guys have meetings or something?”

It would be easy to nit-pick about the Center’s cautious, stilted handling of this least stilted of musical forms. Instead of expounding on “blue tonality” and “text-phrase construction,” why not get down to earth with these kids, who have grown up mostly unaware of the musical sources that mysteriously mutated into Madonna and Bon Jovi?

Why not just tell ‘em that the blues is what you sing when you lose your love, your money, your job; that it’s the song to sing when you feel sad, so that you won’t feel so sad?

We’re talking about music that wells up out of a tortured or enraptured soul. Not microchip technology. I could also have done without the quasi-theatrical setting--a mock recording session--that set up an unnecessary barrier. The blues should be a dialogue between performer and audience, not a “show.”

But in the end, the program was successful despite all the Center’s attempts to dress the blues up, because when it got down to the music, the show gave us the genuine article. And it recognized, however stiffly, that blues--the music created by uneducated, “uncultured” blacks--is as crucial to U.S. culture as opera is to Europe’s.

Cephas and Wiggins mostly stuck to up-tempo blues--which always plays better to short attention spans than moaning, country blues. Still, theirs was authentic, rural folk-blues, not far removed from the kind born nearly a century ago on the porches of sharecroppers’ shacks overlooking dusty dirt roads of the Deep South.

They kept the children entertained and engaged. After the show, Adrienne Cohen, 13, said: “It was better than we expected. We thought it was going to be stupid.” Sarah Pemberton, also 13, agreed that “it was good” (though she allowed that “it’s not something I’d listen to on a monthly basis.”)

What reached these students wasn’t some silly attempt to intellectualize the blues but the direct person-to-person power of the music itself. “That guy on the harmonica was really good,” Adrienne said.

And now that a little real blues has gotten a foothold at the Center--albeit through the back door, for a kids’ show in the tiny downstairs theater--maybe the powers that be will heed Shirley Lind’s advice about the importance of exposure to all forms of arts and culture.

Wouldn’t it be great to see the likes of B.B. King, Robert Cray, Etta James or John Lee Hooker playing in prestigious Segerstrom Hall?

(Though I’d hate to read the program notes: “Mr. King has gained renown in postwar American music as a virtuoso of the six-string, electronically amplified guitar. His skillful juxtaposing of the secular and the spiritual is illustrated when he vocalizes the two-bar stanza: ‘I got a sweet li’l angel/I love the way she spread her wings.’ ”)

Heck, we’ve gotten plenty of opera, i.e., sad musical theater. How about finding room for a little of that sad jazz?