THIS summer, as Wolf Trap begins its 10th season, an irresistible force and a formidable legend are working together in what could prove one of the more productive and dynamic partnerships in the current American art scene. Catherine Filene Shouse has appointed Sarah Caldwell as its music adviser and music director. Whatever the results, the meeting of these two powerful women, each accustomed to sweeping the surrounding world into her own orbit, should prove lively.

Beverly Sills, a participant in Wolf Trap from the beginning and a longtime friend of both women, says: "Mrs. Shouse is a very strong woman with very positive ideas. She and Sarah, both being strong people, will probably have a few goes at it, but I think what will emerge will be very positive."

The partnership is apparently off to a highly congenial start, which finds each woman expressing only praise and respect for the other.

Says Shouse of the 52-year-old Caldwell: "I like working with her because she has a very sharp mind.She's a very intelligent person. We speak the same language and we can evolve ideas together."

Says Caldwell of the 83-year-old Shouse: "We have a great deal of fun together. She has lots of ideas and is very receptive to ideas. We don't have a problem coming up with ideas."

The Shouse legend started assuming its present dimensions when Wolf Trap initiated its first season -- with a concert directed by Julius Rudel. The festival's birth seemed a minor miracle, literally phoenix-like, rising from the ashes of a fire that had destroyed most of the theater just a few months before the scheduled opening. The timing was so close that the last seats were being set up just as the first patrons entered.

"Rehearsals were pure hell," recalls Rudel, "though the results were marvelously exciting. The workers were still sawing and hammering and bulldozing. We tried lowering black velour drapes to cut off the noise but the heat was unbearable."

The person who between March and July 1971 marshaled forces and funds to rebuild and open on time was Wolf Trap's benefactress, Catherine Filene Shouse. Though only one success in a long history of political and cultural accomplishments, that feat was enough to foster within the arts world the reputations of Kay Shouse as a formidable figure of indomitable drive.

An anecdote Rudel tells gives an idea of the impression Shouse created. Surprised by the absence of the airplanes that had disturbed the opening-night concert, Rudel wondered aloud why the skies were empty the following evening. "Haven't you heard?" an arts colleague retorted. "Mrs. Shouse is having them shot down over Maryland."

Blessed with abundant wealth, intelligence, energy and influence, Shouse found it easy to overcome obstacles that might have left others stumbling. (She did, in fact, remove the airplanes sometimes -- (though by the gentler method of simply suggesting in the right place that flight patterns could be altered during performance hours). Over the years the Shouse legend at Wolf Trap thrived, fed on the sensational side by frequent shifts in key personnel who sometimes publicly aired their clashes with her.

The reputation also flourished on Shouse's accomplishments, which included an ability to wade through bureaucratic morasses to get what Wolf Trap needed. When limited access threatened Wolf Trap's growth, for example, Shouse arranged to have special ramps for the then-sacronsanct Dulles roadway open during performances. For the Bicentennial summer she not only brought in one of Wolf Trap's grandest spectacles, the Edinburgh Tattoo, but she also managed to have Prince Phillip in attendance.

Meanwhile, up in New England, another formidable force named Sarah Caldwell was generating her own kind of turbulent energy. Founding her Opera Company of Boston, Caldwell cut a unique path through the performing arts world. She thrived on massive projects, the bigger the better, introducing this country to works that other impresarios were reluctant to tackle. She gave America, for example, its first production of Schoenberg's "Moses und Aaron," an uncut version of Berlioz' "The Trojans" and a powerful staging of Prokofiev's unwieldy 4 1/2-hour-long opera, "War and Peace" (which she brought to Wolf Trap).

In a review of the latter, headlined "General Caldwell Goes to War," The New York Times marveled at her ability to control the vast forces on stage, praising her achievement as "Napoleonic."

In 1976, when Caldwell became the first woman to conduct at the Met, Opera News called her "monumental . . . as irresistible as a military tank."

The Shouse-Caldwell partnership comes at a particularly apt time for Wolf Trap, which seems ready for further artistic development now that its finances and administration are relatively settled. After nine seasons, Wolf Trap has firmly established itself as part of the summer festival scene, helped by annual public television broadcasts since 1974. With a budget that has grown from an initial $1.3 million to $4.6 million this year, its finances are sound. For the last two years, the festival has operated in the black, generating 75 percenet of its income from box-office receipts and raising more than $1 million from private funds. Its partnership with the federal government, which serves as housekeeper for the festival, is working despite a few thorny areas.

Working in what Beverly Sills describes as "probably the most beautiful theater of its kind in the world," Wolf Trap brings culture to its audiences in gentle country atmosphere at prices that are still a bargain. The average ticketed seat cost has not risen in three years. However, though the general public is undoubtedly quite content, many observers of the cultural scene long to see Wolf Trap take on a stronger artistic image.

Shouse is particularly sensitive to criticism in the area of programming. Responding to the observation that some critics find Wolf Trap's offerings too conservative, even to the point of being artistically dull, Shouse replies: "I don't think our audience finds it dull, because they find all types of programs they can come to. Maybe a bluegrass enthusiast finds a symphony dull."

No, some say the bluegrass enthusiasts find the bluegrass dull, to which Shouse replies: "I can only say that bluegrass fills the hall."

What Wolf Trap's seasons have lacked, despite the verdant atmosphere and indisputably high attendance, is that intangible quality known as artistic excitement. Occasionally, Wolf Trap has gone out on a limb in some surprising enterprises -- budgeting over $300,000 for a 1977 production of Busoni's "Doktor Faust," was a striking example -- but, generally, it has sought the safe and sure return.

"Mrs. Shouse wants Wolf Trap to be a family affair," says Beverly Sills, who has had a hand in programming over the years. "With that in mind, you have to plan a particular kind of programming. In the future we may see more premieres. Now that it has established itself, Wolf Trap will probably begin to take some chances, do some more innovative repertoire."

Possibly no one on the American arts scene is better suited to enliven Wolf Trap's artistic image than Sarah Caldwell. Not only does she have a particular gift for translating the innovative into dramatic terms that excite the public, but she is also peculiarly sensitive to the realities of artistic life. Having struggled to establish her own opera company in Boston, she appreciates the fragility of institutions and the necessity of financial responsibility.

"It's easy to come in with all kinds of exciting ideas," says Caldwell. "People like Mrs. Shouse are very responsive to them. She would love to do many, many things. We're going to build carefully. We're going to need time. Certain patterns have worked well at Wolf Trap. It would be foolish to throw them out.

"I'm not worried about having a free hand artistically," adds Caldwell, "but any person in the arts world today has to live in the world of fiscal reality. On the other hand, you can be too aware of finances. Unless you're doing artistically exciting programs, if all your energies are just going into financial stability, then it's not worth it."

Caldwell's touch is only intermittently evident this season, which opens Tuesday with a revival of "Showboat." June 6 she leads the National Symphony in Beethoven's 9th and the following week, from June 12 through 15, she brings her Opera Company of Boston. In July she will conduct her staging of "The Barber of Seville" for the New York City Opera. Beverly Sills has, incidentally, agreed to sing Rosina once more in that production in return for a week's engagement of her New York City Opera company next summer. Caldwell also will stage a midnight performance of a Victorian opera titled "The Vampire" on July 19 and produce Verdi's "Falstaff" with the Wolf Trap Opera Company in August.

For the future, Caldwell plans to develop smaller festivals within the larger season as a means of helping Wolf Trap reach toward its goal of becoming a major international festival. Although the present mixed bag works well for local audiences, Caldwell says that audiences will not come from greater distances unless there are concentrated offerings of their particular interest. This year's five-day jazz festival, put together for the first week in July by John Lewis, is a tentative step in that direction. t

Caldwell also wants to widen the repertoire and develop programs which, in her words, "will be unique rather than programs that can be seen in any one of 10 summer festivals in this country." High on her list is an emphasis on American composers, and a special objective is to commission an opera some day from Elliott Carter.

Shouse praises Caldwell's enthusiasm. "She has a great imagination and a creative way in developing programs. It's been my job up to now." Shouse toys with the idea of retiring next year. "That will [end] our 10th year and I think I should graduate." Could she really live without Wolf Trap? "Yes. I did for 70 years." Another time Shouse underlines her central role. "She [Caldwell] will be music adviser and director. We'll call on her for advice. I'm very happy to have her suggestions, though I still hold responsibility for programming."

Caldwell is positive about her new endeavor. "I find among the people at Wolf Trap enormous good will, an enormous desire to have only the best." She is also realistic. "I'm aware of how precious the existance of an institution is. I'm also aware that institutions come into existence only because a few people will them into being." And she is determined. "We have to develop audiences that are interested in varied repertoire, and we can't develop them until we start doing it. I know that one has to go with deliberate speed. Don't mistake that for patience. I'm not patient. I fret and I worry and I stamp my feet."