"Only this is certain. Through all time to come, this, the 99th Congress of the United States, will be remembered as that body of men and women that either stopped the communists before it was too late -- or did not."

-- Clare Boothe Luce, as quoted by Ronald Reagan

If the president quotes Luce accurately, she has slipped badly. Few public figures of the last half century have demonstrated so great a gift for employing language as a rapier to make a slashing political point, and those supposed sentences of hers that Reagan cites have all the subtlety of a medieval blunderbuss.

It was Luce who called the old New Dealer, Harold Ickes, "a prodigious bureaucrat" with "the soul of a meat ax and the mind of a commissar." It was Luce who demolished the now-forgotten Leroy D. Downs, a member of Congress who had the ill fortune to run against her in 1942, by describing him as "a faceless man who spends a lot of time trying to get his face in the papers."

And it was she whose 1943 maiden speech in Congress, assaulting Vice President Henry A. Wallace and the concept of foreign aid, added a word to the political lexicon. "Much of what Mr. Wallace calls his global thinking is, no matter how you slice it, still globaloney," she said to guffaws from the galleries.

Still, given the historic nature of the occasion to which the president refers, a certain heavy-handedness of style can be forgiven. To hear the president tell it, Thursday's vote on aid to the so-called Nicaraguan "contras," America's mercenaries, rates as the most important congressional roll call of a lifetime, or all time.

Until Reagan's address Sunday night about the menace from Managua, Richard M. Nixon held the presidential record for overstating a case.

Nixon's characterization of the week in 1969 that marked the landing of American astronauts on the moon as "the greatest week in the history of the world since the creation" is hard to top, although his national television address announcing the U.S. "incursion" of Cambodia in 1970 came close.

That's when he warned of disasters that would befall America and the world unless additional U.S. military power were used to stop communists in Southeast Asia. Nixon said: "If, when the chips are down, the world's most powerful nation, the United States of America, acts like a pitiful, helpless giant, the forces of totalitarianism and anarchy will threaten free nations and free institutions throughout the world."

Now Reagan stands in a class by himself. His excessive rhetoric about the "mounting danger in Central America that threatens the security of the United States" posing "a mortal threat to the entire New World," his evocation of the specter of a red tide driving millions of terror-stricken immigrants toward the U.S. border, his equating of the contra aid vote with a politician's final place in history -- all make Nixon on Cambodia seem measured and statesmanlike.

The sad thing is that all of this presidential bombast makes it more difficult, if not impossible, to conduct a serious debate about the best course in Central America. As usual, Reagan talks tough and acts soft. He conjures the most fearsome prospects, then assures the country that his desired goal can be achieved without sacrifice, pain or the exposure to danger of a single American soldier, not even expenditure of an additional dime.

That paltry $100 million he promises will stem the communist tide in Central America isn't even a new request for aid. It is, he says, merely a request "to be permitted to switch a small part of our defense budget to the defense of our own southern frontier."

Assume, for the sake of argument, that Reagan's analysis about the supposed grave threat from Central America is correct. If so, his proposed remedies, expressed passionately in numerous speeches throughout the five years of his presidency, have been a dismal failure. The threat, at least as he describes it, has grown ever more dangerous.

By Reagan's terms, members of Congress should not be debating whether to make a most minor switch of funds in the Defense Department's accounting books. They should be voting on whether to blockade Nicaragua, interdict its sea and air lanes and prepare for introduction of U.S. military force to safeguard American citizens and the hemisphere. They ought to be asked to send in the Marines.