"History is a dangerous thing," Isabel Letelier, widow of former Chilean ambassador Orlando Letelier, told a group gathered in a Mayflower Hotel ballroom last night. "It's rewritten every day in authoritarian regimes . . . The value of the human rights community is that we have good memories. We keep records. We don't forget."

It is touted as part commemoration of slain colleagues, part exhortation of human rights causes. The ninth annual Letelier-Moffitt Memorial Human Rights Awards Ceremony was held last night in the names of Orlando Letelier -- an official of the Institute for Policy Studies here and a colleague of former leftist Chilean president Salvador Allende -- and Ronni Karpen Moffitt, a young IPS staffer. The two were killed in September 1976 when the bomb-rigged car in which they rode exploded in Sheridan Circle in one of the worst acts of terrorism ever in Washington.

"This is a gathering of some of the hearts that can think in this country," said Chilean-born novelist Ariel Dorfman, looking around at the human rights activists who were part of the 260 who dined in a ballroom that is often the scene of more well-endowed conservative groups.

And IPS director Bob Borosage also made it clear that in a time of conservatism, when "reporters occasionally come by to see if we're still around," the group has no intention of leaving the scene.

Rep. William H. Gray III (D-Pa.), chairman of the House Budget Committee and last night's keynote speaker, told the group, "We have seen the lights go out to a certain degree with political rights." But, he entreated his audience, "We ought to remember how we got here -- by fighting, by lighting candles, by going in the dark."

The liberal Institute for Policy Studies, sponsor of the awards, this year singled out the Free South Africa movement, which last year initiated the antiapartheid protests in front of the South African embassy, "the match that lit the political firestorm of the year," according to Borosage. They also gave an award to the Mutual Support Group of Guatemala, which seeks information about the relatives of the disappeared in that country. And they honored Canadian activist Frances Arbour, who has spearheaded numerous efforts to promote human rights in Latin America.

Sylvia Hill, a member of the Free South Africa Movement and a professor at the University of the District of Columbia, said that the protests had successfully "weakened the ties between the Reagan administration . . . and South Africa" but that public pressure must continue: "We want to see clearer foreign policy that opposes U.S. collaboration with South Africa."