As people poured into the National Shrine's crypt church yesterday, someone shouted, "Be quiet in the presence of the Lord," in a voice colored with emotion and distress. His request went unheeded by the steady stream of people who filled the seats and then the aisles and then the side chapels and the entrance hall. Amplified by the cavelike acoustics, their footsteps and quiet conversations sounded like a reverent roar.

It was a mass, the opening liturgical service of the Symposium on Gregorian Chant in Liturgy and Education, which is bringing church scholars and musicians to Catholic University this week, and the choirs, or "Scholae," were from the Camerata Gregorian Coloniensis in Cologne, from L'Eglise St. Pierre-aux-Liens, in Bulle, Switzerland, the Boston Archdiocesan Choir School and St. Paul's Church in Cambridge, Mass. And what marvelous music they made, drawing out the timeless lyricism with weightless legatos and astonishing unanimity of vowel sounds.

The mass, its music and the buildings built to house it are among the more miraculous examples of unity in this world. In a sense, they represent the perfect drama on the perfect stage. The architects who designed cathedrals (among them, the National Shrine and its crypt) knew what they were about. Maybe polyphony gets scrambled into mush by those acoustics, but chant takes on an otherworldly glow and a sense of endlessness in those vast spaces.

The structure of the service, as it has evolved, balances the sounds of the individual, the choir and the congregation in a larger rhythm that has its softest moments as its climax and its most exuberant as release. It was splendid to hear the Gregorian melodies phrased so beautifully, and gratifying, in light of the church's moves to modernize the service and its music, to hear a large congregation negotiate the shapes of the Gloria, the Credo and the rest so expertly and with such evident affection.