Mozart is such an exalted figure that he has reached the status of monument. The composer stands for refinement, purity, exquisite beauty, genius embodied in human form — even after he has been depicted as an adolescent monster on stage and film, and his bizarrely scatological humor, bawdy proclivities, and spendthrift ways are exposed in detailed biographies that focus on the celebrity rather than the Enlightenment artist. Mozart proves that beauty stays, however it may be assaulted by the waves of fashion, politics, and theory — the tsunamis of history.

An artist, however — especially one as serious as Alison Harney — can't play a monument. The notes on the page may have been composed by a genius in Salzburg in 1775, but when Harney puts hand to bow, sets fingers upon strings, cradles her violin to the nape of her neck in a St. Louis studio in 2007, she is engaged with a living thing.

"It really is difficult," she says of Mozart's Violin Concerto No. 5, which she performs March 2 and 3 at Powell Symphony Hall. "It's one of those every-note-a-pearl kind of pieces. The margin for error is very small."

In a downtown St. Louis Nepalese restaurant, the SLSO's Principal Second Violin pulls back her long, red hair as she speaks. As she describes the difficulties and the pleasures of playing Mozart, she sometimes presses her fingers on the tabletop, extending those long fingers as if she were finding the appropriate chords on a piano. "The more you listen to this work," she explains, "and the more you play it, the more you know of the many options and timings Mozart is offering you."

Harney first performed the Concerto with a freelance Los Angeles orchestra after winning a competition at age 13. "It must have been fine," she says with a laugh. "It's not one of my traumatic memories."

As she pursued her career, she played the piece for orchestral auditions. "I performed it for Daniel Barenboim, among others," she recalls. "But when you know you're going to play with an orchestra you dig deeper. The context becomes larger even as it becomes more detail-oriented."

Harney is heartened by the fact that the guest conductor for this program is Nicholas McGegan, who possesses a deep knowledge of both the large context and the intricate details of Mozart. McGegan also specifically requested Harney as the soloist. "Nic is going to be a delight to play with," Harney says. "He sees where all the characters in Mozart's music are, and he knows how to bring them out through the whole orchestra."

When Harney refers to "characters," she is expressing a new approach she has taken with the concerto. "I started to tape myself and heard that I was taking a quasi, early-music approach," she explains, "and I found it was not effective. Then I took notice of Mozart's tempo marking, Allegro aperto, which I've only seen in one of his operas. 'Aperto' means 'open,' which was key in helping me understand the vocal nature of the first movement's ebullient Allegro. And I thought, if I were a singer, how would I approach this?"

Harney further develops this operatic theme. "I was reading an interview with [pianist] Piotr Anderszewski. He was talking about a whole underworld of emotions living beneath Mozart's melodies. I now see the A major as the most operatic of violin concerti — certainly the first movement. And the second movement is a stunning example of Mozartian genius. I truly recognize it as an aria, as singing exquisite music that transcends violin playing.

"There are so many operatic characters in this work. You have your coloratura soprano, mezzo-soprano, tenor, and bass characters. They're all in there. And then the emotions and voices — who's singing what and how — changes on a dime. You can imagine all these characters talking to each other."

Yet with an understanding of the operatic grandeur of the piece, Harney is left to the discipline and diligence required to make that grandeur heard. When asked what, for her, are the thorny sections of the concerto, she sighs, "The thing about Mozart is they change from day to day. One day the most dreaded part magically works. Then the next day it isn't working, so I constantly have to apply my brain and analyze technically what I'm doing. There are technical things I have to struggle with to express what I want to express."

She enlists colleagues to help, to play with her, to listen, encourage, and cajole. "I hope to have five or six run-throughs at least three weeks before the full rehearsals," she says.

And she has her own personality with which she must negotiate. "I have this personal dichotomy: I am very hypercritical and hypersensitive with my playing, yet I take huge musical risks. I can't help it."

And there is the lofty Mozart. But after a plate of comforting Nepalese cuisine and a cup of warming chai tea, and after talking the concerto out for an afternoon, Mozart is not so much the matter. Rather, Harney finds herself at home with the real nuts-and-bolts work that needs to be done, and with the joy of it — the reason Mozart has been worth the struggle for musicians across the centuries. "No matter what," Harney confides, "when I get to the second movement, I know this is what I'm supposed to be doing."

Eddie Silva is the publications manager for the Saint Louis Symphony Orchestra.