BOSTON — FOR more than two decades, Boston's Emmanuel Church, Episcopal, has performed Bach cantatas as part of its Sunday services. The cantatas have been a training ground for the city's many student musicians, a musical gift to the community, and a spiritual uplift for individuals.On the recent 200th anniversary of Mozart's finishing "The Magic Flute," Emmanuel performed the opera as a special AIDS fundraiser - to glowing local reviews. Here the Monitor's editor, Richard J. Cattani, interviews Emmanuel's music director, Craig Smith. @BODYTEXT = How long have you been doing this program of cantatas? For 21 years, since 1970. It started from very little. I was a student, and others were students, at the New England Conservatory, and we started it very casually with a series of eight weeks in the spring - and we've been going ever since. We give at least 40 performances, nine months every year, plus our special events now, such as Mozart's "Magic Flute." Do you start in with cantata No. 1 and let it rip? The cantatas go by the readings for the church year. The Episcopal prayer book was redone during the last five years, so now it's a little harder. We spend a long time planning the whole service so that the readings, prayers, and music line up. Was Bach a good Episcopalian? No, he was a very good Lutheran. Yes - but is the Lutheran composer's music appropriate for your Episcopalian service? The theology of Bach's time is very stern - everybody is sinning all the time. It's more severe than modern-day Lutheranism. It's funny that we're at this incredibly liberal place [Emmanuel Church] where everyone is included, but every week we stand up there and say, "You know, you're all going to hell." But it's wonderful stuff. If you're "going to go to hell," maybe that's the way to do it. I think that it is. Actually, the words are wonderful. They are in a style that is not current but they are very much from the heart. There are about 200 Bach cantatas extant. We've done them all, about 38 each year. You would think that after 21 years I would be tired of them, and I keep expecting to be. But I never am. That goes for everybody. We have mostly regulars who have played here and sung here for a long time. We have a chorus of about 20 and an orchestra, a pool, of 25 to 30 regulars. Every Boston musician seems to have played at Emmanuel at some time. Ten years ago I counted 35 oboists who had played at Emmanuel, and I'm sure it's up to 50 by now. Some come back for special performances. The greatest body of music ever written is the Bach cantatas. That is really what has kept us all together. Is anybody else doing these cantatas ad infinitum? Yes, actually, in Leipzig, in Bach's church, St. Thomas Kirche. I don't know what has happened since the two [German] sides have gotten together. But here was the Thomas Kirche, with 10 old ladies on Sunday morning for the service, and then the state put on this very expensive, elaborate weekly performance of a Bach cantata in the afternoon. It was out of context; the Christian context was not allowed. Bach probably wrote 150 cantatas in Leipzig. He arrived in 1723 and stayed until his death in 1750. It was presumed the cantatas were created over that entire period. But all of them were done by about 1728, over a five-year period of time. At least a hundred others are lost. Bach became very depressed and stopped writing. Bach, depressed? The situation was very bad. The discipline of the little boys [at St. Thomas] was disastrous. An endless string of children were either born dead or died in the first week of their birth. That must have had some effect. His music is considered very lofty and impersonal, but the truth is that he was this very fiery person who even spent a week in jail. He was difficult, irrascible. The town council said, "Why do you write such difficult music? You know in Berlin Telemann is writing all this nice, pretty stuff. Why don't you write stuff like that?" He became terribly depressed and did almost nothing for 20 years. When Bach wrote before he got to Leipzig, he had good players. The parts are often virtuoso. And then he wrote in that same style for Leipzig and clearly was very burned in some of the performances. The parts get easier and easier and easier, so that by the end, he really doesn't really trust anybody, and everything is written for organ. Because that he knows, that his son, Carl, Philip, or Emmanuel will be playing it - and it will be all right. And then it just stops. His last works are didactic. They c over the techniques of keyboard play, of fugue writing. He must have realized he was the greatest composer that ever lived. And that nobody could play his music. So he wrote it for the ages. What does Bach's music do for the Boston community? For the musicians, it is the greatest honer of skills and technique possible. The musical ideas are very speculative and complicated. They have very odd ideas theologically. This week's cantata is a huge, vulgar metaphor about money: "The capital of your sins pays interest in your suffering." The text was by one of the preachers at his church. The whole text of another cantata, for Trinity Sunday, about baptism, is about taking a bath. It begins, "Oh holy ghost, the water bath of the soul ... use the soap of the scriptures." It's in German. There's a genuine drive, which comes from Luther as opposed to the Catholic tradition, of wanting every single person in the congregation to understand these concepts, and of using the most homely, low-down metaphors to communicate them. Is that what you meant by "vulgar" a moment ago? It seems vulgar to us because we're so used to underplaying the capitalist element in the Christian church these days. Bach's symbols work in a Jungian fashion. People respond unconsciously to a shared reservoir of ideas. Bach, remember, had some 20 music books in his library when he died, and 200 theological books. His goal was to be one of two minsters of the church. Sometimes it all seems ho-hum. And then on a snowy February Sunday there will be someone in the audience that the music speaks to so strongly they just don't know what hit them.