American Ballet Theater at Metropolitan Opera House Herman Cornejo in "The Dream," a highlight of the American Ballet Theater season. To watch American Ballet Theater today is sometimes to witness ballet history being made. The company ends its eight-week May-to-July season at the Metropolitan Opera House on Saturday with "Le Corsaire." But in Frederick Ashton's one-act "Dream," the season's most illustrious and perfect production, the company is, from top to bottom, at least as good as today's Royal Ballet (for which Ashton created it in 1964 and which remains the world's foremost specialist in his style). Ballet Theater, in fact, is often better. "The Dream" features exceptional difficulties of coordinating upper-body plasticity with intricate footwork and vivid legwork; Ballet Theater's artists lap up these challenges. Members of American Ballet Theater in "La Bayadère." Ashton (1904-88), were he alive to coach them, would probably assign eye exercises to most of the Oberons and all the Titanias (as he did to Anthony Dowell and Antoinette Sibley, his famous first-cast couple in this ballet), and he would most likely cry, "Bend!" and "More!" (his two favorite words in rehearsal) to everybody. Ashton would agree that Herman Cornejo's Puck, a fairy of both earth and air, is the most miraculous account of an Ashton role by any non-Royal dancer since Mikhail Baryshnikov danced in "La Fille Mal Gardée" in 1977. In most respects the company also dances and acts Kenneth MacMillan's "Romeo and Juliet" at least as well as today's Royal. MacMillan created this for the Royal in 1965, permitting a remarkable divergence of interpretations among his first four pairs of star lovers: Margot Fonteyn and Rudolf Nureyev, Lynn Seymour and Christopher Gable, Ms. Sibley and Mr. Dowell, and Merle Park and Donald MacLeary. He restaged the ballet for Ballet Theater in 1985. Only this season - with casts including Diana Vishneva and Marcelo Gomes, Gillian Murphy and Cory Stearns, Natalia Osipova and David Hallberg, and Alina Cojocaru and Johan Kobborg - was the ballet once again enlarged by an equally prestigious diversity of interpretations. My guess is that MacMillan would have worked hardest with Ms. Vishneva and especially Ms. Osipova (who came nearest to changing his choreography), but he would have relished the challenge. "Romeo" interpretations in recent years have conformed too much to one mold. Every Juliet, when finding Romeo's dead body, now does a silent scream, which used to be peculiar to Ms. Seymour alone. No Juliet ever writhes on the balcony like a cat in heat, which used to be a more radical stroke of Ms. Seymour's - she once said in interview that was her "rip-off" from Judi Dench's famous Juliet in Franco Zeffirelli's 1960 Royal Shakespeare Company production. Yet this season's Ballet Theater casts once more shook up and stretched the ballet's dramatic potential. And that doesn't even include the greatest "Romeo" performance of all: Mr. Cornejo as a Mercutio full of fantasy and mischief, so persuasively Veronese, at once an educated Renaissance gentleman and a modern rebel, tugging the heart in the brilliance of his musical timing and his dramatic absorption. Older balletgoers will remember the days when the Royal danced New York seasons at least once every two years between 1949 and 1976; New York was the Royal's second home and the city where Ashton felt his choreography was best appreciated. Today's Ballet Theater has come increasingly to resemble the Royal in its repertory, while the Royal has come to resemble Ballet Theater in its international selection of principals. The main difference is that the Royal retains a more pronounced local style (line, musicality, acting) in which its foreign stars are painstakingly trained. Other Ballet Theater season highlights also occurred, though intermittently, in performances of Natalia Makarova's three-act version of "La Bayadère." As with David Walker's designs for "The Dream" and Nicholas Georgiadis's for "Romeo," PierLuigi Samaritani's designs are never better than on the vast Met stage, as in his "Bayadère." Yet more remarkable is Toshiro Ogawa's lighting of the famous Shades scene, casting a near-phosphorescent glow upon the legs of the 24 women of the corps de ballet. No company now dances this celebrated scene as well as Ballet Theater. American Ballet Theater's season at the Metropolitan Opera House ends on Saturday; (212) 362-6000, abt.org.