The table is being set when the musicians begin to tune their instruments, after which the conductor walks onstage resplendent in formal clothes. On October 14 that ritual will be enacted once again when the Atlantic Symphony Orchestra opens its 21st season at Thayer Academy Center for the Arts in Braintree with a performance of Mozart’s Symphony No. 25, often referred to as the “Little G” symphony.

When the lights go down and the first notes soar the audience prepares itself for a few hours of bliss. That’s what beautiful music delivers — an opportunity to dream, to imagine, to be beyond the mundane, the worrying, the frightening.

The table is being set when the musicians begin to tune their instruments, after which the conductor walks onstage resplendent in formal clothes. On October 14 that ritual will be enacted once again when the Atlantic Symphony Orchestra opens its 21st season at Thayer Academy Center for the Arts in Braintree with a performance of Mozart’s Symphony No. 25, often referred to as the “Little G” symphony.

Only 17 when Mozart wrote that piece in 1773, it nevertheless has been described as his “first decisive step from wunderkind to great composer, from entertainer to artist.” The symphony became popular in the modern era when it was featured in the film “Amadeus.”

The other work on the program is Berlioz’ Symphony Fantastique. Unlike any piece that had preceded it when it debuted in 1830, and inspired by the unrequited love Berlioz had for a British actress (whom eventually he did marry), the work startled audiences for its being different from anything they had ever heard before.

Fellow composer Robert Schumann — who was fully aware of the torment Berlioz was enduring while composing the symphony, since Berlioz freely shared his misery with others — reviewed an 1835 performance of the piece, attempting to capture in words the overwhelming feelings he’d experienced while listening to the first movement:

“This man, so highly musical, barely 19 years old, of French blood, exuberant with energy, battling moreover with the future and perhaps in the throes of other violent passions — this man is seized for the first time by the god of love — not, however, that timid feeling that prefers to confide in the moon, but rather the gloomy fire one sees at night pouring forth from Etna…And here he sees her. I imagine this feminine creature to be like the main theme of the whole symphony, pale, slender as a lily, veiled, quiet, almost cold…. while its tones burn into one’s very entrails.

Read in the symphony itself how he rushes toward her, eager to surround her with his soul’s embrace, and then recoils breathlessly from the coldness of the British woman; how he offers, with renewed humility, to lift the hem of her dress to his lips, and then stands proudly erect and demands her love, since his love — for her — is so terrifying: read it again, for it is all written there in the first movement with drops of blood.”

Symphony Fantastique — declared to have ushered in the romantic era of music — would be a challenge for any orchestra, in that Its demands are great. Consisting of five movements, the symphony will take up the whole second half of Saturday’s program. And being extremely complex, the work requires a large number of musicians, all of whom must be in sync at all times, not an easy task since Berlioz laid bare on the page his wildly clashing emotions, often produced by morbid visions, which he managed to translate into thrilling and disturbing musical passages.

We who have followed the Atlantic Symphony over the 20 years Jin Kim has been its musical director have no doubt that this fine orchestra will have no trouble replicating for us the profound experience Schumann had 182 years ago.

ASO president

A wonderful conductor and brilliant musicians are mostly all we in the audience know about the ASO. Few of us stop to think about what — besides rehearsals — goes into a performance like the one that will be presented this weekend. A rare glimpse of behind the scenes is when Karen Flynn Thompson, president of the ASO, makes an on-stage appearance at some point in the program.

Smart, attractive and enthusiastic, Thompson lives in Hingham, with her husband Carl, who owns an ad agency, and her three children, all of whom are involved in the arts.

During a recent interview at ASO’s office in Weymouth, Thompson proudly described her children’s interests: “Cole is studying animation at Mass Art, Nick does sound for productions at the high school, and Hope is involved in a production of ‘Chicago,’ also at the high school.”

She then added, “Carl, himself is a fabulous artist.”

Thompson, too, makes art, on a computer, which over the past year she has used to “build the organization’s infrastructure,” by which she means the staff, the folks who answer the phone, promote the organization, do fundraising, sell tickets, pass out programs, solicit ads for the program, man snack tables at intermission, and greet people as they enter the venue where the performance will take place. A handful are paid staff; the rest are volunteers, men and women whose reward is to see the ASO continue to make marvelous music season after season.

Actually, Thompson is one of those volunteers, a person who has put on hold for a period of time her profession as an educational content developer in order to help move the ASO ahead by expanding its board and widening its regional impact.

Loathe to promote her own contributions to this growing institution, she stresses that the learning curve for her at the ASO had been a slow one.

“I didn’t feel ‘presidential’ until our concert last March at Jordan Hall, when we celebrated the orchestra’s 20th season.” That was five months into Thompson’s tenure, which had been launched publicly — rather hesitantly by her — at last season’s opening concert.

One year later she is obviously at home in the belly of an arts non-profit, non-profit meaning it is the type of organization that does not earn profits for its owners, that all of the money earned by or donated to the organization is used in pursuing its objectives and keeping it running.

One might think that non-profit refers mainly to small enterprises, since individuals aren’t profiting from the organization’s successes. But many non-profits are huge, including hospitals, academic institutions and foundations, whose leaders certainly do profit by earning big salaries. Of course, large arts organizations also are part of that mix, such as the Boston Symphony Orchestra and the Museum of Fine Arts, which are revered internationally and are more than a century old.

Relatively new regional arts organizations, like the South Shore Art Center and the Atlantic Symphony Orchestra are a different story. Instead of having a big money machine to prop them up, they must rely on the community they serve to pay the bills and spread the word. That can result in some days being cliff-hangers.

Such a challenge requires huge effort and great dedication, which is the case with the ASO. That is borne out by the fact that over the two decades it has been in existence the symphony’s reputation and audience have grown, and have continued to do so under Thompson’s leadership.

During our discussion Thompson pointed out that an orchestra has an obligation other kinds of arts organizations don’t have. “We have to keep a group of musicians employed.”

Indeed, most musicians — like small non-profits — live in an uncertain world, where every day they’re looking for the next gig. With that as the norm, to have a fixed booking over a year is a blessing for these talented artists.

Smiling broadly, as she frequently does, Thompson summed up her feelings about a job she’d never considered having: “I am so appreciative for what we have, and so lucky to be part of it.

And her ultimate goal for the ASO?

“To be well-known, well-done and well-loved.”

The concert will begin 7:30 pm, at Thayer Academy Center for the Arts, 745 Washington St., Braintree. Tickets: $25–$47 for adults and seniors; $15–$20 for students. Reserved seating can be purchased by phone at 781-331-3600, or online at