THE SCREECH of the White House leak pluggers is abroad in the land. I can remember is peculiar timbre all the way back to the Trumman days. Real old-timers still hear its echoesfrom the Hoover administraton.

The leak seekers never learn. They are the kind of people who wear Gucci shoes and natural-shoulder, hand-tailored suits, but they keep epaulets under their pillows.

They don't understand the leakers because they don't understand the public's love-hate affair with the newspapers. Leakers are like ear syringes. The more pressure one puts on them, the more they squirt into our ears.

For 30 years now, my ears have been awash with leaks, with Jack Anderson, but also with the Hearst newspapers, The Washington Post and others. Where most people hear ringing in their ears after they pass 50, I hear whispering.

President Reagan and his mahouts are baffled by the psychology of leaks. Reagan complains that leaks are at "a new high here . . . leaks that are destructive of the foreign policy."

Assistant Defense Secretary Henry E. Catto Jr. huffs about "the principle of the thing . . . the expression of minority policy opinions via leaks." White House spokesmen David R. Gergen and Larry Speakes try to explain why practically every agency head from the CIA to Fish and Wildlife wants hunt-and-destroy missions against leakers.

And then there is the dumbfounding sight of Deputy Defense Secretary Frank C. Carlucci volunteering to take the first lie-detector test to prove he didn't leak secrets from a meeting he chaired.

Why do leakers leak? They do it for a variety of reasons. Presidents do it to get their thoughts across without having to take responsibility for them. Or as trial balloons. Or sometimes, they, being no more decent than the rest of us, use leaks to destroy their enemies.

Cabinet members and agency heads tend to follow the presidential psychology on leaks. While lesser folk may leak out of friendship, idealism, even whimsy, at the top level the motive is more often self-interest, malice and anger. Whatever it is, it is Washington free enterprise in action.

Leakers come in many archetypes. There are the Idealists, the Avengers, Friends and Mad Bombers.

At its most artistic, leaking is a form of expression that can rival the grands jete's of Baryshnikov, the cadenza of a Chopin or the brush stroke of an El Greco. 'Capital of Leaks'

The master of the leak-qua-art is Lyn Nofziger, the waggish Til Eulenspiegel of this otherwise self-important administration. It is worth noting that he just jumped ship with a remark about his rat-like prescience.

Nofziger understands that hanging leakers may require a two-branched gibbet and one of the branches may be the present executive branch. Nofziger knows his history. He lived it.

After all, a Watergate document informs us that "Whenever possible Nofziger" -- then a high Nixon official -- "planted stories favorable to the Nixon administration with newsmen, on his own or at the request of H.R. Haldeman . . ."

The document goes on:

"After the California primary, Nofziger sent a person from the Committee to Re-Elect the President into the California McGovern office . . . in an attempt to find a form which purportedly told McGovern volunteers how to get on welfare." Had Nofziger's ingenuity paid off, which it didn't, he would surely have leaked it to a friendly reporter.

Indeed, he generally was more successful. In another caper before he joined the Reagan White House, he used a chain of friendships to squeeze documents from the office of a rival presidential candidate.

To his delight, they showed that the seemingly prim and proper aspirant had misused federal funds. Nofziger leaked the documents to a reporter. The story made the candidate look like a hypocrite and probably was a factor in his dismal primaries showing.

Nofziger is anything but unique. Leaking in Washington is good business. Richard L. Strout of the Christian Science Monitor, who calls it the "Capital of Leaks," recounts how an irate President Kennedy once ordered his press man, Pierre Salinger, to root out a leak. Salinger gleefully reported back that Kennedy himself was the culprit.

More ominously, Bobby Kennedy's Justice Department went to considerable lengths to ruin what was left of Jimmy Hoffa's tarnished reputation. When the Teamsters boss was arrested for slugging a weaker aide, a Justice official leaked out the news even before the police reports were typed up.

The beat reporters at Washington's Metropolitan Police headquarters were staggered to see a herd of political reporters arriving at the booking desk on a story they themselves knew nothing about.

More recently, Jody Powell, the Carter press spokesman, was almost drowned in his leak of an untrue rumor about Sen. Charles Percy (R-Ill.), with whom Carter was then piqued.

And clearly those stories about the secret workings of the Reagan White House have come directly from the President's most intimate circle. If Reagan intends to stop leaks, he can begin with some of his closest breakfast and lunch companions.

Outside the White House, the most outraged of the anti-leakers seem to be secretaries Alexander Haig of State and Caspar W. Weinberger of Defense, Central Intelligence Director William Casey and the new national security adviser, William P. Clark. I can guarantee that at least three of these in the past have given confidential material to the press.

Leaking, after all, is consonant with the Reagan hoopla on free enterprise. If leaking stops, so does this Washington; it is that vital to getting the administration's message across.

How else would we know about Reagan's views on tax increases, Social Security, future Pentagon spending -- and civil rights? How else would the recently removed White House security adviser, Richard V. Allen, have been put on the skids by his administration adversaries?

And aren't leakers carrying out to a "t" Reagan's philosophy of voluntarism, of rugged laissez-faire individualism? What is more gloriously free-enterprising than a leaker throwing off the shackles of federal regulation -- anti-leaking regulations in this case? The Mad Bomber

Richard Nixon, as we know from the tapes, eagerly sought to get vicious stories out about his enemies. His and his inner circle's targets included Gov. George Wallace, Democratic leader Lawrence O'Brien and a supreme leaker himself, Daniel Ellsberg.

Lyndon Johnson, in private talks with a reporter, fulminated against his attorney general, Robert Kennedy, and was happy as a yearling when some of his rumors got into print.

Nor can I ever forget the furious whisper of a postmaster general as he leaked sensitive material to me about one of his underlings whom he suspected of being in charge of a CIA operation within his department. That vast old office seemed to heat up with his anger at the CIA for refusing to tell him what was going on. I could not prove out his information. Later, Watergate showed how accurate his suspicions were.

One of Nixon's top five aides, on the way to jail, gave me an FBI report on a pre-presidential love affair of President Kennedy. "You've done your share on this president," he said, meaning Nixon. "Let's see if you've got the guts to do something on Kennedy." I never wrote the story. It was 25 years old.

It even happens with nice guys. A Ford lieutenant leaked me material designed to knock Sen. Howard Baker (R-Tenn.) out as Ford's vice presidential choice. It seemed to have worked. Ford chose Sen. Robert Dole (R-Kan.) and lost.

These, though, are the royal leaks that can defame the mightiest or even change history. It is clearly not these that the White House wants to staunch. Reagan's foremost advisers are not lemmings. If leakers at the ultimate level are discovered, Reagan advisers will be among them.

The leakers they seek to dry up or force into some mea culpa session as a lesson to other government employes are the uncontrolled leakers.

But their approach could hardly be more silly. Although the Reagan administration is awash with old Nixonites, few seem to recall that it was in the most vindictive days of the plumbers that the leaks became most diluvial. The Nixon ship of state was like the Jumblies' sieve.

White House memos warning leakers are the surest way to stir their adrenaline.

George Metesky, who years ago set off explosions in New York and waited excitedly to read about them in the papers, is the patron saint of mad bombers. His psychology is precisely like that of the finest leakers. Both operate on the brink of disaster.

These are the people Reagan is trying to tell to stop leaking. Is the president crazy? These wonderful people aren't deterred by his ukases. They're stimulated by them. They are people with a dream.

The classic Mad Bomber explosion was detonated by the Footsoldier of the First Amendment who sent the Dita Beard letter over Jack Anderson's transom in 1972.

It exposed ITT's fancy dealings with the Nixon administration and its release led to congressional investigations, grand juries, resignations, convictions, disclosures of CIA and other government wrongdoing, among other things. To this day, we do not know the bomb thrower's identity.

Yet I have often imagined a typical Mad Bomber in situ. He -- or she -- bored and frustrated, spots the irresistible memo on a colleague's desk: the report of some awesome federal boondoggle, of a felonious senator, of a hidden depot of poison gas near some small American town.

The "Top Secret" stamps blossom on the document like the ribboned seals on a Paraguayan general's commission. The threat of punishment is dire. Yet the Mad Bomber cannot stop himself. Something Walter Mittyish in him makes him pick up the document by its edges, sidle down the hall with it to somebody else's Xerox machine so the telltale dots on the copy, if it ever falls into investigators' hands, will put them off the track.

He returns the original to his colleague's desk and sends the copy in a fingerprintless envelope to his reporter of choice. Then like Metesky, he waits for the action. The Idealist

Nor is it only the Mad Bombers who will increase proportionately to how hard the Reagan administration tries to suppress them. So will the Idealistic leakers. There are in government many people who think that if there's poison gas outside somebody's home town, then the townspeople have a right to know about it.

Years ago, an Army colonel walked into my office in full uniform to give me some information. After I had taken it all down, I asked him why he didn't come in mufti. If we were being watched by the CIA or FBI as we were off and on in those days, then the uniform would have started the bells tolling, and all of them for him.

"I would have felt I was doing something wrong if I hadn't come in uniform," said that naive, marvelous military hero.

The old-time patriotism being preached by Ronald Reagan requires us to be ready to die for our ideals -- perhaps even for the ideals of some tinpot dictator in El Salvador or Guatemala. How could Reagan not know that there are decent people in government who are going to liberate documents gathered with public funds -- also in the name of old-time American idealism?

As examples, during the Vietnam war, a time also of pressure against leakers, it was an American diplomat in Laos who leaked us the fact that we were bombing peasant villages there; and it was another American diplomat who lifted 99 pages of classified documents to give us the ghastly details of Operation Phoenix in which we were making pho soup of Vietcong and innocents alike.

Finally, Reagan's crackdown will encourage our old friends.

Not two days after the latest warning to government leakers, an old source, one I had not heard from during the comparatively benign Ford and Carter years, called me at home. The pretense was to catch up on my family. At the end, the source said:

"I'll keep you in mind if anything comes across the desk."

Sources are like amateur skiers, surfers, hang gliders, parachutists. They like the danger, in this case the thrill of participating in something forbidden. But things have changed since the Watergate days.

Due to what I call the All-the-President's-Men-syndrome, sources will no longer meet you in a convenient Wheaton bar. They demand at a minimum a rendezvous in an underground garage before they will agree to pass you classified documents.

The more exotic the locale the happier the source. The deputy to a well-known post-Watergate political personage wanted to upend his boss. He had the papers. He wanted to meet.

I tried the Whistler room at the Freer on him, an old favorite since few FBI or CIA operatives are interested in Whistler. No, said my finicky source. I tried the swings at Montrose Park. No, too cold.

Finally, his politics in mind, I suggested the giant elephant at the Museum of Natural History. Yes, he said, perfect. The added symbolism did not escape either of us: The elephant has been demasculinized in order not to offend schoolchildren whose eye level is elephant-belly high. The papers helped drive his boss from office. Meet Me at the Archives

No doubt, Ronald Reagan believes he is doing the nation's work when he cracks down on leakers. But what most classified material contains are facts to which the public has every logical right.

Why shouldn't newspaper readers and TV addicts hear about these tales of bad boys and boondoggles? Why should they not learn about the hilarious buffoonery of the men with the secrecy stamps?

The most thoroughly classified piece of paper I ever saw was no more than a newspaper story on author James Baldwin who was then under CIA and FBI surveillance because he happened to believe in civil rights. The stamps on the document read "Secret -- No Foreign Dissemination" in four different places, and for good measure, "Group One: Excluded from automatic downgrading and declassification . . . Racial Matter."

What this highly secret document, whose possession outside the intelligence community was a criminal offense, told us was that "there are times when he [Baldwin] writes continuously 24 hours without food and water . . . Afterwards he lies down and sleeps."

Aren't those who "declassify" documents on an ad hoc basis and give them to the press as good public servants as the bureaucrats who indiscriminately classify them?

Maybe that eunuch elephant was the wrong place to meet my source. If he calls again I will have a suggestion for him. I would like to meet him at the National Archives near a copy of the Constitution of the United States. Leakers and that much-abused old document may have something in common.