The majestic ease of Ballet Theatre

Classical ballet - at its best - gives to the human form nobility, grandeur, grace. Its long, tempered lines and symmetrical stage patterns, joined by regal costumery, produce something as close to majesty as we come these days.

The American Ballet Theatre, under the firm hand of Mikhail Baryshnikov, is dancing very close to these standards of late, as was evident at one of the closing performances of its spring season, which ended last weekend. The June 9 program at the Metropolitan Opera House featured Baryshnikov dancing in his own restaging of ''Les Sylphides'' and two new ABT productions - Kenneth MacMillan's ''Triad'' and Natalia Makarova's restaging of Petipa's ''Paquita.''

If one phrase could define the performance that evening, it is majestic ease. The company, corps included, danced with a stirring confidence and authority that, added to their technical expertise, produced a program of four scintillating ballets.

The evening opened with ''Sylphides,'' the curtain drawing up on a stageful of sylphs in flowing white skirts framed by a deep, tall forest; in the center was the commanding presence of Baryshnikov. Any opportunity to see him dance these days is a rare treat (which is unfortunate for ABT, which has been having trouble selling out the Metropolitan Opera House without him or Fernando Bujones on stage). The great danseur noble proved he was in fine form - dancing with effortless height, strength, and charm.

Partnering with Baryshnikov was Marianna Tcherkassky, who brought her own version of restrained elegance to the dance, especially evident in her solo to one of Chopin's famous preludes. But the real heart of this ballet is the pas de deux, and in this, Baryshnikov and Tcherkassky were teamed to excellence. One particularly delightful section had Tcherkassky stepping steadily forward on toe while Baryshnikov danced backward toward the audience, hopping and turning as he went. All the while she hovered over him, holding a motherly smile that encouraged and admired him; the rapport between the two was marvelous.

If anyone was disappointed at the lack of dramatic leaps and turns in ''Sylphides,'' he got his pyrotechnics in the next piece. ''Sylvia - Pas de Deux'' was danced with nearly flawless execution by the young Patrick Bissell and the glamorous Martine van Hamel. In solos, both provided their own series of breathtaking moves, and Bissell's triple pirouettes followed by turns en l'air were special crowd pleasers. Again, the rapport between partners was enchanting, each handclasp and each presentation tuned to perfection. You got the feeling that as they were charming the audience, they were also charming each other - which was confirmed by van Hamel, who, during the thunderous ovation, plucked a rose from her bouquet and presented it to Bissell, with him kissing her hand upon receiving it.

Next came ''Triad,'' which, in stark contrast to the rest of the evening's program, is a modern, dramatic ballet marked by a rigorous, athletic style of movement. The story is typical ballet material - of a boy and his brother both in love with the same girl - and the mood is highly emotional: The performers wear fiery red body suits and dance to Prokofiev's dramatic ''Violin Concerto No. 1.'' One of the signature moves in the choreography is a lurching, top-to-bottom rolling of the back - which both begins the ballet and ends it.

Johan Renvall was a powerhouse as the frustrated younger brother, dashing about the stage in great bursts of energy, then curling up like a little boy and crying. But it was Robert La Fosse who continued the evening's theme of majestic ease: At one point, after Renvall was beaten up by the Girl's companions, La Fosse went to save him, dancing a thrilling series of leaps and turns, with arms and head high and gesturing upward for authority. Amanda McKerrow was sufficiently sassy and elusive as the Girl, although not nearly as captivating as some of her fellow female stars.

In fact, it was in ''Paquita,'' by Makarova (who is one of the greatest of prima ballerinas), that the company's women really came out to shine. From the moment the corps of 14 women entered, you knew something special was happening on stage: Smiles aglow and in shimmering light orange dress, they paraded in by threes and fours, dancing with a zesty flair. The mood was definitely Spanish flamenco, with hands held high and the movement snappy, but with a strong, noble line. Fernando Bujones, with his charismatic Latin look, was ideal as one-half of the lead couple, Cynthia Gregory being the other half.

In all, it was a night of splendor for the American Ballet Theatre, and one hopes the company can continue this level of excellence in the future.

ABT will be performing in Philadelphia Aug. 21-30 and in Japan for three weeks starting Oct. 25.