"We didn't know how good we were doing," said Frank Capra softly. "Very few of us knew that we were working in an art form."

The 82-year-old director's voice was tinged with surprise and a touch of awe at the thought that the films he made are now treated as classics, studied at universities and preserved in the National Archives. He has given seminars at 125 universities in the last few years, and last night he was honored, together with fellow director Pare Lorentz, at a reception in the National Archives.

"I still get queasy about coming to Washington," he said, recalling the controversy raised in the late '30s by his "Mr. Smith Goes to Washington."

"I'm always afraid that someone's going to chase me out of town. You know, the day after we showed it for the first time, the United States Senate voted 'thumbs down' on it. They voted 96 to 0 that it was a total caricature of that great institution, the U.S. Senate, and should be banned -- and there were only 48 states -- 96 senators -- at that time."

Lorentz encountered less controversy with classics such as "The River," which was shown last night at the Archives along with Capra's "War Comes to America," but he recalled other kinds of trouble.

"I wanted 'the river' to open in New Orleans, not New York," he recalled, "because it had a lot of southern material and I was afraid the New York critics would kill it. So I went to New Orleans and I walked around and found a theater that was offering four westerns for a dime. I went to the manager and asked him if he wanted to show a world premiere, and he said he's never had one but he didn't see any reason why he shouldn't.

"He warned me that when they didn't like a picture, the patrons of his theatre were inclined to throw rocks at the screen and make holes in it, but I didn't think there would be any problem. As a matter of fact, when the name of Robert E. Lee was flashed on the screen at the end of his message of surrender, everyone in the audience stood up."

At the wine and cheese party, after the films were shown and the directors had given their introductory remarks, Capra and Lorentz were chatting together when someone mentioned that some footage in "War Comes to America" had been lifted bodily out of "The River."

"Sure," said Lorentz. "He took some material from 'The Plow That Broke the Plains,' too, but that was all right, because we were both working for the government."

Capra produced all of his World War II documentary films without a shooting crew of his own (and with equipment that was "borrowed or stolen"), making new films out of footage that had been used originally in other pictures -- much of it from German and Japanese news and propaganda films.

A cameraman who contributed some choice footage to Capra's films was at the reception last night, reminiscing about going to war with a camera. He was Norman Hatch, who was the only movie cameraman on Tarawa for the first day and a half of the military action there, and whose work was prominent in an Academy Award-winning documentary on the battle. "It wasn't hard to cover the whole battle because the island was so small you could be in touch with everything," he said, "but there was so much smoke in the air that I worried about having the right exposures. I was so concerned about not getting it right that I didn't have time to worry that they were shooting at me."

Capra recalled worrying that people might be shooting at him after the first sneak preview of his "Lost Horizon." "The audience was coming out saying things like, 'They ought to shoot people who would make a picture like that,' and we found out that the problem was in the first two reels -- without them, we had a picture and with them we didn't. So I took those two reels, the prints, the negatives and everything connected with them, went out to the incinerator and illuminated the night sky of Hollywood. Those old nitrate films would really burn. By the next day, I had such negative feelings about those first two reels that I had totally forgotten what was in them. Now, I don't know and nobody else does, either."

Black tie was optional at the reception, which also marked the issuing of a catalogue of several dozen documentary film classics being distributed by the National Audio Visual Center. While Lorentz opted for formality, Capra opted for the Hollywood look -- a jacket in large brown and gray checks, canary-yellow trousers and a bright yellow V-neck sweater over a bright red turtleneck. His recollections were equally colorful.

"After the experience with 'Mr. Smith,' I was really worried about how Washington would react to 'State of the Union,' which is a much more bitter picture and cuts a lot deeper. 'Mr. Smith' is a fairly easygoing story about a young idealist who runs into reality, but 'State of the Union' dealt with the way a political party picks its candidate -- lots of backstage stuff and quite a few Harry Truman gags.

"Truman came to see it, and I told my wife, 'Pack; we may have to go to Mexico,' and Truman and the politicians loved it. Truman took a print of it to his boat and was running it every day for his friends.

"Later, after Truman was reelected, his campaign manager came out to Hollywood and gave a talk. He said that 'State of the Union' had changed Harry Truman's life -- that seeing that picture had made him decide to run for reelection, and he went to the people, speaking from the back of a train all over the country, and he won it."

Capra speaks fondly of all his old pictures -- even the silent comedies he was making back in the '20s, and a puzzled look comes on his face when he comes to "It's a Wonderful Life," which he made right after World War Ii but which was not fully appreciated until long after its original release.

"A film in the can is nothing at all," he says. "It just sits there -- useless. But when you project it with an audience, it has a life and power all its own, completely out or your control. That can scare hell out of you -- you realize that you are working with something precious, something dynamic."

"We didn't always realize what we had when we were shooting or editing a film. A few people in a small screening room just don't have the same reaction as a big audience in a theater. We would think we had something pretty good, and take it out for a sneak preview and 1,000 people would tell us we didn't.

"In the '30s and '40s we had no idea that people would still want to see these films 40 years later -- a lot of them were burned after their run to recover the silver, which, was about five percent of the cost -- and now they're gone; nobody saved them.

"We thought what we were producing was like news papers -- you look at them once and then throw them away."