STEPHEN HESS, the baron of sound bites, is one of the Washington experts whom journalists prize for his ability to squeeze insights on complex issues into 9-second quotes for TV. He also comes up with instant, pithy, and highly quotable phrases for newspaper and magazine reporters on deadline.When it comes to talking about himself, though, Stephen Hess is no "beitmeister," but a man who struggles, often rewriting as he talks, to express what concerns him most. He sits in his book-paved office at the Brookings Institution where he is senior fellow in governmental studies and talks about what drove him out of government and into his present role as Boswell to the national news media. His new book, "Live from Capitol Hill!" an engrossing study of Congress and the media, has just come out, publis hed by Brookings. Mr. Hess is viewed by the press as a nonpartisan source, from a famous think tank with "no hidden agenda." He says, "I am above the fray, but obviously I didn't start above the fray.... I started in politics, I got here in politics." He explains, "Watergate was a very seminal experience in my life. I was a biographer of Richard Nixon, had been his speechwriter at one time, was on his staff in 1969 as deputy assistant to the President for urban affairs, basically Pat Moynihan's chief of staff, and out of the administration by the beginning of 1972. During the Watergate hearings I was the PBS analyst with Robin McNeil and Jim Lehrer and usually a fourth, a law professor on TV. So I sat there during the Ervin hearings [Sen. Sam Ervin D-S.C.] on Watergate all day, every day.... I started getting nightmares to the degree to which I thought of this as a real corruption of the democratic process and system, and the people whom I knew well. They were my colleagues.... "And I resigned on the air. One day I said I can't come back tomorrow. I said why. It was very nice, the crew on the set petitioned me to come back. And I've never worked in the government since." He adds he has done "little occasional things," translated: being US representative to the UN General Assembly and also to the UNESCO General Conference. Hess is an amiable-looking guy with pearl gray hair and inquisitive blue eyes. He leans back in his chair in his Brookings corner office overlooking "Embassy Row" on Massachusetts Avenue and fields questions on his new book. A chunk of his days is spent fielding questions from the news media. In 1988 he logged 1,294 calls from 183 news organizations in 17 countries. And they're not just sound bites or quotes for deadlines. Hess acts as a sort of media Yoda (the wiseman in "Star Wars") because of his rather cosmic range of experience as an insider: presidential speechwriter, assistant to the minority whip in the US Senate, syndicated newspaper columnist, and author of 11 books on politics and government. The last four are part of the Brookings Newswork series on the press which he began in 1981 with Newswork I: "The Washington Reporters" followed by Newswork 2, "The Government/Press Connection", Newswork 3, "The Ultimate In siders" (Senators and the media), and now Newswork 4: "Live from Capitol Hill!" Hess himself is seen too as an "ultimate insider." Just before our interview, a Canadian reporter had called him, saying the Bush Administration hadn't used the phrase "New World Order" since March, and wondering if they'd retired the phrase. Hess steered him off in a possible direction for a story source. Another reporter called, about a piece on the presidential "1,000 points of light." Hess suggested talking to Peggy Noonan, the speechwriter who coined that phrase. He gives quick, precise answers to wire service reporters on deadline ("no schmoozing") and background information to general assignment reporters. He says he feels almost like "a switching service" some days. But he draws the line at going out to studios for sound bites. m happy to be useful, with other people you talk on the telephone. But for me to go to CBS and do a sound bite and come back frankly would take half of my day. It's not my job." In his new book, "Live from Capitol Hill" Hess characterizes the congressional press galleries as one big newsroom, where a keen herding instinct is present among reporters, and less visceral competition than among the White House press corps or "the State Department and Pentagon where they take their cues from diplomats and generals." Chapters focus on: the press gallery; watching the watchdog; reporting live from the Hill; press secretaries and press releases. Op-ed pieces, and the celebrity status of being covered on TV are treated in Hess's incisive, fly-on-the-wall style in this 178 page book. Hess, a Johns Hopkins graduate, is also a frequent contributor to a wide range of magazines and newspapers, from The Atlantic to the Los Angeles Times, as well as a commentator (BBC, Canadian Broadcasting System, PBS) and lecturer (at nearly 50 colleges, universities, and public forums). His next book is on how the US media cover international news.