For about half an hour Saturday night in the Kennedy Center Concert Hall, it was like the mid-'60s again. The music was new, but the feeling of the event was familiar; so were some of the words, whose rich spoken cadences made their own special kind of music.

"I have a dream . . . ," said Willie Stargell at the evening's climax, and a current of electricity ran through the audience. The orchestra rose to a crescendo as the voice continued, riding atop the music like a ship on a swelling ocean: "The dream is one of equality of opportunity . . . a dream of a land where men will not take necessities from the many to give luxuries to the few . . . the dream of a country where every man will respect the dignity and worth of all human personality, and men will dare to live together as brothers . . ." The voice ended; the music dropped to a deep hush: barely audible strings punctuated with touches of metallic percussion.

The spirit of Dr. Martin Luther King Jr., who died in 1968, lived again on what would have been his 54th birthday. His presence was evoked partly in the music, the world premiere of Joseph Schwantner's "New Morning for the World," but much more directly in his own words, interwoven with the music composed in his memory. The text (including an "I have a dream" speech written long before the famous one given in this city) was chosen from King's writings over a 10-year period. It was spoken by Stargell with quiet dignity and an imposing stage presence--with superb pace, expert phrasing and carefully calculated emphasis. The music was played by the Eastman Philharmonia, a student orchestra from the Eastman School of Music in Rochester, N.Y., with the power and precision of a professional ensemble.

Schwantner has been drawing much of his musical inspiration from words since the mid-'70s; besides vocal music (such as his cycle "Wild Angels of the Open Hills," which will be performed here later this season), there have been several works inspired by texts that were not actually spoken or sung but, resonating in the composer's mind, helped to give the music its flavor and structure. His two best known recent compositions, "Aftertones of Infinity," which won the 1979 Pulitzer Prize, and "Music of Amber," which won the 1981 Kennedy Center/Friedheim competition, had such unstated texts. "New Morning for the World" uses its texts not only for inspiration but as part of the music--sometimes its most powerful part, though the music is also eloquent.

The Schwantner premiere was not the only one on the program; also given its first performance was "An Eastman Overture" by Washington-born George Walker, the dean of living black American composers: a tight-knit, brilliantly orchestrated and dramatic work that epitomizes the special character of the Eastman School, Walker's alma mater. This school has long had a special dedication to American music, and particularly to orchestral music in a fairly conservative idiom. Walker has given it a tasty addition to that repertoire and one that will tell the listener a lot about the organization that commissioned it. In his terse program note, the composer mentions "suggestive allusions" to Bach, Beethoven and Brahms; he might also mention the late Howard Hanson, founder of the Philharmonia and for many years director of the school, whose spirit lives again in Walker's music as King's does in Schwantner's.

Throughout a long (slightly too long) evening, the performances were good by any standard and remarkable for the work of a student orchestra. Besides the two premieres, the program included two American classics, Copland's "Appalachian Spring" and Barber's "Adagio for Strings," as well as Walter Piston's magnificent Fourth Symphony, which runs a wide gamut of lyricism, wit, brilliance, drama and riotous color in its four brief movements.

For a showcase of music appropriate to Eastman's traditional tastes, it was a brilliantly chosen program, though it ran beyond two hours including the intermission. Despite the length, it would be hard to pick a candidate for omission; certainly not either of the premieres, and hardly either of the two items from the American classical top-40. That would leave only the Piston Symphony--but it was arguably the best music on the whole program.