Ravi Shankar picks up his sitar for no musical reason at all -- to have their picture taken together. As he poses, his fingers move instinctively over the strings and a morning raga spontaneously begins to happen. Low strings set up a steady hum that fills Shankar's room at the Watergate like the aroma of the incense stick burning in a corner.

Treble melodies leap out and sparkle like the stray sunbeams filtering through the window -- melodies always the same but constantly changing. Sometimes the sitar sounds more like a human voice than a set of vibrating strings; sometimes the strings sound bowed rather than plucked. The notes bend and slide into pitches unknown in western classical music.

"That is a raga I have played many times," he says, putting his instrument down. "But it was never quite like that before and it will never be quite like that again. Each time, the raga is new -- little touches are always different."

When Ravi Shankar plays, as he will tonight at the Kennedy Center concert opening the year-long nationwide Festival of India, the performer and instrument merge into a single reality. "It doesn't seem to be a dead instrument," he says. "It is alive. This is true, I think, for anyone who has given his life to an instrument.

"My music is a religious act; there is still that feeling," he says. "When the music is not written down and you learn by an oral tradition, that attitude remains the same. What is transmitted by the guru is not merely a technique but a feeling. My guru taught me that the best way to worship is by music."

In the 1960s, this quiet man was a superstar -- as readily recognized as Mick Jagger, though he gave off a different sort of vibration. The sitar, known only to a handful of ethnomusicologists and devotees of Indian art in the 1950s, became a cult object to the flower children, almost as powerful as the amplified guitar, the mantra, the strobe light or marijuana in its power to evoke altered forms of awareness.

The Beatles, probably the most influential musicians of the '60s, showed Shankar's influence in their landmark album, "Sgt. Pepper's Lonely Hearts Club Band." George Harrison, who was once a disciple of Shankar, remains a close friend. Today, Shankar is still a superstar long after Cream has curdled, Donovan has disappeared and the Jefferson Airplane has crashed. He was there, in his quiet way, before them and he has shown (as might have been expected) more staying power.

Shankar looks back on the '60s without apologies or regrets; it was something that came and has gone away; but there remains an essentially positive residual interest in the sitar and the music of India. "I have been coming to America for 30 years," he says, "and in that time I have seen a very great change. There was a big boost in the mid-'60s, then it fell back to normal. Now, it is rising again, more slowly but more solidly, naturally. It would have happened anyway, but a little more slowly. It is a gradual thing. There is always a new generation that has to learn -- again and again. If 10 million people become aware of the sitar, perhaps 10,000 will become more deeply involved."

Before the '60s, Shankar's muscial associations were all classical -- eastern and western. "I was very lucky as a little boy," he says. "I sat on Andre's Segovia's knee in Paris when I was 10 years old. I was with my brother Uday, the famous dancer. Be'la Barto'k used to come to visit." His first teacher was Ustad Allaudin Khan, whom he called "Baba" -- father.

Shankar, 64, was the first Indian musician to make a strong impact in America -- partly because, as one who had sat on Segovia's knee when he was 10, he knew more about western concert life. "There is an incorrect notion in India that the longer the raga is, the purer. It is true that, with the right audience, a raga lasting 2 1/2 hours can seem like just 15 minutes -- but that has to happen spontaneously. In this country, you have union rules about the times for starting and stopping a concert, and there must be an intermission. When I began here, I was criticized because I would give audiences only as much as they could take. Now, audiences can take much more.

"But still, to be paid for a performance here, you have to go to a concert hall and switch yourself on at the appointed time. It is not the traditional way with this music, but we cannot avoid being in this age."

His concert arrangements in this country are still essentially western but slowly moving closer to the traditional Indian style. "Now," he says, "I do not decide even the raga I will play until a half-hour or 15 minutes before the concert. At that point, I can say, 'This is what I feel tonight.' I have stopped giving printed program notes or advance announcements of the program. It is hard to put yourself into the mood of a printed page."

In Shankar's music, as in the jazz or flamenco music to which it is related in some ways, the interaction between the musician and audience partly dictates the form the music will take. "With the right audience," he says, "you have a built-in inspiration. I like to have music students sitting in the front for feedback. When it does not come from the audience, I have my colleagues; many things go on between us and are reflected in the music. We have an immediate, spontaneous response that comes through strongly.

"After 30 years, I can feel that response more and more from audiences in the United States, too. The average Indian music-lover has grown up with the music, while Americans have been hearing it for a few years only -- but amazing attempts are being made to understand. On both coasts, East and West, we find a lot of wonderful listeners. Some who began in the '60s and stayed on have developed a very high level of appreciation."

When he plays, Shankar seems to be in another world. You might say he makes his frequent trips to America as a representative of that other world -- a musical ambassador, or perhaps a missionary. Talking about his work, Shankar uses a more neutral term; he is a bridge.

"Cultural bridges are the best," he says. "In American newspapers, you read about mishaps in India, about catastrophes and cultural upheavals. But there are many important things you never hear about. India has one name, but it is many countries. It is not like the United States or France; it is more like Europe, with 14 or 16 main languages and thousands of dialects, some of them spoken only, not written. In all this variety, we have one link: our old traditions, including our religious background."