It was a one-day course--call it "India: Culture, Politics, Cuisine and Security" -- as Prime Minister Rajiv Gandhi addressed Congress yesterday, then toured a Smithsonian exhibit and hosted a dinner for Vice President Bush before the official opening of the Festival of India.

"I wish everyone in this room could have been up in the U.S. Capitol today," Bush said in his toast at the Kennedy Center dinner. "You did an outstanding job and everyone in the U.S. knows it."

Or if not absolutely everyone, at least the 200 people at the Kennedy Center's Atrium, who applauded heartily. Eating Chicken Kandhari (i.e., curry with cashew nuts and cream), Kabab-e-Koht (i.e., mutton cubes marinated in yogurt) and Raspberry Soup (i.e., delicious) were Secretary of State George Shultz, Defense Secretary Caspar Weinberger, former ambassadors Sen. Daniel Patrick Moynihan and John Kenneth Galbraith, and astronomer Carl Sagan, who met with Gandhi earlier in the day to discuss the nuclear arms race.

"It's exceeded everything expected," Shultz said of Gandhi's visit. The festival, while more concerned with dancers and ancient sculpture than disarmament and nonalignment, has a salubrious effect on diplomacy as well, Shultz said diplomatically.

"It was started as a result of Indira Gandhi's visit several years ago, which from my own perspective was very important because it was my first state visit as secretary of state. It was an important visit in U.S.-Indian relations. I think they've benefited since, and this one will move them forward."

B.R. Bhagat, a member of Parliament and chairman of the foreign relations department of the Indian National Congress, said Ghandi worked until 3:30 Thursday morning on the speech he delivered to Congress that day..

"We are very pleased," Bhagat said of the entire visit. "The prime minister has said nothing -- he is like that."

Bhagat said he had been a freedom fighter in India's struggle for independence from Britain, and that he spent three years in a British prison. Gandhi, however, is of another generation.

"He is a very simple man," Bhagat said. "He is sincere about everything he does."

That sincerity, Bhagat said, endears Gandhi to the Indian population.

"It is the most important quality to them," he said. "You can be a clever man, you can be an intelligent man, but if you are not sincere they will not like you. We call it credibility."

In his toast to Bush, who celebrated his 61st birthday Wednesday, Gandhi was brief, saying little more than, "To much better understanding between the American people and the Indian people, and to your birthday."

Which is not to suggest it was a casual affair. Nothing with a receiving line and tuxedoed Secret Service men scattered around the room can be called anything near casual.

After dinner the guests attended the opening Festival of India concert. Indian festival chairwoman Pupul Jayakar said she hopes the 18-month festival will show Americans "the reality of India. As India is, rather than what anyone imagines it to be. They usually think of India of 5,000 years ago, or they think of India of the maharajas or the raj, or they think of India as great poverty. They don't see that there is a strain of tremendous vitality."

Nancy Reagan got a chance to experience some of the vitality earlier in the day, when she joined Gandhi and his wife Sonia in a tour of "Aditi: A Celebration of Life," a Festival exhibit at the Smithsonian's Museum of Natural History.

In a week when police seem to dot every street corner within two miles of wherever the Indian leader is, the exhibit was a security agent's nightmare -- from the metal detection of the man with two heads to the flower shower over Mrs. Reagan.

For the Gandhis and Nancy Reagan, the tour may have made their lucky day. The shrines, the intricate floor paintings and the figures of gods and goddesses gave a blessing, according to Indian scholar M.N. Deshpande. "These things are auspicious, protective," he said. "Prosperity, wealth, good things from all four corners come from the Mandana and Rangoli floor paintings."

The security team was more concerned with technical rather than holy protective devices.

Consider the problems in running through the metal detector the Indian bahrupiya (impersonator) who was rigged up with two heads, a hunchback and an extra set of hands and legs. The dancers and other artists and performers, festooned with silver chains, rings and bracelets, wearing many wrappings of silk saris woven with metal threads, set off the alarms. They had to be gone over with hand metal detectors.

The Secret Service was horrified, an observer said, by the prospect of actually burning the multitiered diya (a bronze Indian lamp) at the entrance. The forces of light prevailed -- Mrs. Reagan, the Gandhis with India's festival chairwoman Jayakar, and S. Dillon Ripley, the U.S. chairman, used a candle to ceremonially set fire to the lamp's oil. Rajeev Sethi, Aditi curator, hung the official party with wreaths of roses. The party then followed a path of feet and plant floor drawings by Ganga Devi to pass through the exhibits of huge ceramic horses and miniature statues of demons, and what Protocol's Patrick Daly called "tarted-up elephants," stuffed and sequined cloth.

Deshpande, who catalogued and documented the Gandhi and Nehru collection of Indian art some years ago, said the prime minister made a good guide for Reagan because of his knowledge of Indian culture.

Mrs. Reagan looked surprised and blinked when the wedding procession performers, including a centaur, danced around her and suddenly threw flowers head to toe over her and Sonia Gandhi. In the next exhibit the Bhopas, story scroll balladeers from Rajasthan, seemed safely up on the platform, singing and dancing the Rajput epics with great gusto. Unexpectedly, the 9-year-old Shish Ram and 4-year-old Kailash leaped down from the platform and danced around Reagan. The Secret Service observed closely as magicians Chand Pasha and his son Yusef pulled linking scarves from a box.

For Mary Ripley and her husband Dillon, it all seemed very familiar. "I first went to India during the war," she said. She said she couldn't remember how many times they had been to India, where they live in tents while studying birds, "but it's our second home."

Meera Bajpai, the wife of the Indian ambassador, said she thought the Aditi experience would reveal some of India's complexity to Nancy Reagan. "Americans are so open to ideas. Aditi shows that the poorest peasant in India lives intensely, sometimes it's intense misery, but there are many moments of intense happiness. Indians know how to have joy."