LIKE PEOPLE who spend their nights gazing at the moon, the political/journalistic community is abuzz about its latest photographic discovery: the dark side of Mario Cuomo.

Rotating out of view is the image of Cuomo as Sir Thomas More -- as the cerebral Catholic who conveyed an air of goodness when he defied church doctrine at Notre Dame University, the valiant governor who defied New York voters by opposing capital punishment, the eloquent speaker who electrified the 1984 Democratic National Convention. Rotating into view is Cuomo as a combative street-fighter -- an insecure Queens pol with a mean streak camouflaged by a priestly pose of sanctimony.

The small community of journalists and politicians who are presidential-watchers now focus on these dark questions: Why does Cuomo seem to whine so? Why did he recently threaten to run for president in order to dispel "increasing references to my ethnicity"? Why did he ludicrously assert that it was "baloney" to claim that the Mafia existed as an organization? Why does he seem so thin-skinned, attacking the motives of those who oppose him? Why, in recent months, has he made a series of gaffes that have angered state legislators and Mayor Edward I. Koch? Why is it persistently said that he trusts few, delegates poorly and is surrounded by a weak staff?

The two sides of Mario Matthew Cuomo were described well 33 years ago in a scouting report on the then 20-year-old centerfielder with the Pittsburgh Pirates' Class D farm team, the Brunswick (Ga.) Pirates. Composed by scout Edward McCarrick and sent to Branch Rickey, then with Pittsburgh, it said of Cuomo:

"Potentially the best prospect on the club in my opinion and could go all the way if he improves his hitting to the point of a respectable batting average. He is aggressive and plays hard. He is intelligent and is a straight A student at St. John's University. He will probably graduate summa cum laude. He is not an easy chap to get close to but is very well-liked by those who succeed in penetrating the exterior shell . . . . He is another who will run over you if you get in his way."

This appraisal remains a prophetic summary of the man many Democrats and Republicans alike believe "could go all the way" to the White House. And it is an appraisal which suggests that critics, or believers, are merely gazing at different sides of the same complex man, a man whose assets are often his liabilities.

To believers, Cuomo is a combative man of principle; to critics, he is an inflexible New Deal liberal. He is alternately described as righteous or self-righteous, as a man with deep ethnic and family roots or a man who is deeply provincial, as someone of rare intelligence or clever cunning, as a skilled conciliator or a plodding incrementalist, as a dedicated public servant or a pol "who will run over you if you get in his way."

There is a bright and a dark side to Cuomo. The bright side is the combative man of principle who, in 1982, was convinced he could defeat the favored candidate of the Democratic establishment, Mayor Koch, for the gubernatorial nomination. Cuomo dared stand alone -- as he has in vetoing the death penalty, or in persistently speaking of government's "compassionate" role, or in defying church elders who proclaim that a Catholic public official has a duty to obey his church and oppose abortions, or by insisting, against an avalanche of staff advice, on leading the national battle to maintain the federal income-tax deductibility for state and local taxes.

Cuomo is not easily diverted, and he often dazzles opponents with verbal gymnastics. The dean of men at St. John's University once spotted Cuomo in the hall with a lighted cigarette and ordered the undergraduate to his office.

"What for?" Cuomo asked.

"You're not supposed to smoke," the dean exclaimed.

"Did you see me smoking, Father?" Cuomo asked. "Is there a rule against carrying a lighted cigarette?" "Are you going to tell me you weren't smoking?" the dean asked.

"No, Father. But I'm not going to tell you that I was. I have shoes on, and yet I'm not walking."

It is perhaps revealing that the same story, almost word for word, is told by biographer Robert Caro about another Democrat -- the young Lyndon B. Johnson, a political operator few would associate with Mario Cuomo.

The dark side of Cuomo's playful combativeness is that he sometimes treats disagreements as courtroom confrontations. Like the Queens lawyer he once was, Cuomo often insists on getting in the last word. However, what works in a courtoom can come off as narrow or petulant in a different setting.

This December, for example, the governor got into a verbal joust with reporters in his office. They tried to elicit his thoughts on the Mafia. He acknowledged there was a Mafia but said it was only one faction of organized crime. Reporters pressed. And Cuomo, foolishly adopting what he calls "a Socratic dialogue with a reporter," said: You're telling me that Mafia is an organization, and I'm telling you that's a lot of baloney." It was a careless game to play, one which wrongly portrayed Cuomo as a naife or a stooge for the Mafia.

In his combative way, Cuomo sometimes questions the motives of those who disagree with him. A few years ago he wondered aloud how a conservative like William F. Buckley could be a good Christian since he opposed compassionate government programs to assist the poor. Those Republicans who challenged his efforts to grant clemecy to a cop-killer were attacked for their "political" motives. At a recent seminar at the New School in New York City, I asked Cuomo a question about his tax policies and he stunned many of the 500 or so people in attendance by proceeding to cross examine me and by launching an attack on the motives of all journalists. Later, members of the audience wondered whether Cuomo harbored a personal grudge or was a zealot. The truth, I think, is that he was just acting like a trial lawyer.

Cuomo denies he is thin-skinned or has a tendency to snarl and go after people's motives. "I think that criticism is a joke," he said in an interview last week. "No one who makes that criticism can pretend to know anything about me. How can you be too strong an advcocate and have gotten Ossining?" During the Ossining prison riots of 1983, Cuomo patiently negotiated a settlement that spared lives without excusing those who violated the law. "When you need to cajole and conciliate," he said, "then I have a reputation for being the best in the business."

Assuming that Cuomo is now flirting with the idea of running for president -- something even he no longer denies -- the political liability of such heated words is that Cuomo can appear mean-spirited. As noted by conservative strategist Roger Stone, "His meanness clashes with the air of goodness" he otherwise conveys. At a time when voters yearn to learn the character of those who would occupy the White House, a personality trait that seems at war with a politician's overall image can be devastating. Jimmy Carter's appeal as a "good man" soured when he turned nasty. Gary Hart's "freshness" was spoiled by his strangeness. George Bush's "experience" was sabotaged by his preppy whineyness.

The bright side of the righteous Cuomo is that he is a man of inner conviction, one whose admiration of Sir Thomas More is advertised by the portraits of More that loom on his office walls and in the living room of the five-bedroom Cape Cod house his father, Andrea, built in Queens for Mario and Matilda Cuomo. Believing it would be wrong to abandon a pledge to serve a full term as governor, Cuomo rejected overtures from Walter Mondale to serve as his vice presidential candidate in 1984.

It may be telling that St. John's, where Cuomo graduated summa cum laude and first in his law class, is a Vincentian school, unlike Fordham or Holy Cross, which are Jesuit schools. "The Jesuits are trained to educate," Cuomo once told me. "The Vincentians are trained missionaries."

Cuomo recounted his mission in the diary he published in 1984 -- "Diaries of Mario M. Cuomo: The Campaign for Governor" -- this way: "Always, the nagging truth is that I should be something else -- a person who gives only to give, who works only to provide, who speaks only to soothe or persuade for the good, who strives only for others. nd always there is the depressing reality that I fail utterly at that truth, that my emotions are at war with it -- or at least are too strong to surrender to it."

Almost daily Cuomo makes entries in the diary he keeps, trying to decipher what he believes. Mario Cuomo is more introspective than most politicians, a trait that critics once thought made him Hamlet-like. Unlike many politicians, Cuomo need not consult a poll or survey his advisors to decide what he believes. He is secure enough to talk mostly to himself. "I did use the diary to examine myself," Cuomo once explained. "Some people would use a confessor; some would use their spouse or a close friend; some would go for a walk in the woods and talk to themselves. I talk to my diary. It's a way of inquiring into my own motives."

The dark side of this brooding trait is that Cuomo can be almost monkish. This "hard-to-penetrate" man rushed home from San Francisco right after his keynote speech to the 1984 Democratic convention, wanting to be alone rather than mingle with delegates. He was eager to get back to work and to speak to his diary. Some who know him suspect that this devout Catholic is really speaking to the only audience that counts -- God. To some this is as frightening as Jerry Falwell's personal pipeline to God, for it conveys the anti-democratic notion that those who don't share the same religious pipeline are somehow less virtuous. The appearance of virtue matters to Cuomo. His preferred pose is to behave as if overt ambition is somehow sinful. Witness the variety of dodges he concocted to deny interest in running for president, all since abandoned because they seemed coy.

Another luminous side to Cuomo is that he is a man, as his two published books suggest, with an acute intelligence. He believes that there is a "reasonable" position that most can find. Because he can frame issues in ways that appear reasonable, and because he can be charming and funny, the side of Cuomo that is conciliatory has led to relatively harmonious relations with the state legislature and such former foes as Ed Koch. For those looking for a new kind of Democrat, Cuomo's "progressive pragmatism," as he dubs it, renders him more moderate than his rhetoric sometimes suggests.

Judged by what he calls "the prose" of governing rather than the "poetry" of rhetoric, Cuomo is building a moderate if unexciting record that may play nationally. As governor, he has continued New York's incremental tax-cutting efforts and has, for the first time since Nelson Rockefeller's reign, moved to close an unpublicized $4 billion deficit by appropriating state funds to narrow this gap. He has been generously non-partisan, as when he appointed Republicans to the state's highest court, including the post of chief justice. After years of delay, he succeeded in prodding the construction of such development projects as a new convention center (naming it after former Republican senator Jacob Javits), the mammoth Battery Park City and a redevelopment plan for West 42nd Street. Without being profligate, he has enlarged state efforts to assist the homeless and teen-age mothers.

With Sen. Edward Kennedy's exit from the 1988 contest, Cuomo may be able to emphasize his relatively moderate record as governor. "Kennedy's withdrawal," observes a former Democratic congressman, "allows Cuomo to be more moderate because it means that no one will be to the left of Cuomo, except maybe Jesse Jackson."

The danger for Cuomo is that without Kennedy in the race, he will be pushed to the left and tattooed as a liberal. This is the view of those who see a darker side to Cuomo, for they glimpse in his intelligence a glibness that masks a reflexive liberalism. The eloquence of his heralded speech to the 1984 Democratic convention, for example, blinded many to the fact that Cuomo's was a 1930's portrait of America, a land of rich versus poor, "a tale of two cities," with only a whisper about America's now-dominant middle class. Reflexively, Cuomo endorsed the more liberal Walter Mondale as the Democratic candidate for president, and he staunchly opposes as anti-labor any experiments with a sub-minimum wage for unemployed youths or with a variety of civil-service reforms. Although Cuomo lambasts President Reagan's unwillingness to curb the defense budget, he shies, like most New Deal liberals, from proposing specific curbs in any entitlement programs.

The bright side is that Cuomo is a man of certitude. Cuomo knows who he is -- a Catholic from Queens who is proud of his mom and pop, his Italo-American heritage, his wife, Matilda, and their five children, his unwavering belief in government's helping role. He is unafraid to obey what he calls "powerful instincts". Unlike many in public life, he can converse about subjects beyond himself. He reads books, and compared to most public officials, he is probably an intellectual.

The dark side of this man of certitude is that he can seem smug. He is intellectually curious -- during the preparation of his first budget in 1983, he shut his office door one afternoon and sat down to read William Kennedy's novel, "Ironweed," a bleak account of a homeless stumblebum. But he has not been curious about travel or foreign policy.

Cuomo has not visited most of the 50 states. He has never been to western Europe, save for a brief visit to Italy and a pause in Spain. He has never set foot in Eastern Europe, in the Soviet Union, in Israel, India or China, in the Near, Far or Middle East, in Africa or South America. Nor has he sought out foreign leaders. During last fall's 40th anniversary of the United Nations, when nearly 200 heads of state or foreign ministers came to New York, the governor was a near recluse. The only foreign leader he met with was Italian Prime Minister Bettino Craxi, who requested the meeting. On another occasion, he spurned French President Francois Mitterand's breakfast request, fearing such contacts would look like he was running for president. Instead, he looks -- and may be -- provincial.

The bright side of Cuomo is that he can inspire. The most recent public opinion surveys report that his approval ratings climb well above 70 percent. Voters seem to like the man. Perhaps they sense that Cuomo is largely unaffected by the glitter of his high office. He remains friends with school chums and next-door neighbors. Rarely does he venture out to mingle with seductive strangers who offer campaign contributions or glamor.

He is a proud Italo-American, wounded by ethnic slights. His emotional reaction to the use of the word "Mafia" is a common one among Italo-Americans who seize on the word as an ethnic slur. No doubt this is related to the anger Cuomo still feels toward the 100 or so law firms that once discarded his resume. Although he shone as a clerk on the state Court of Appeals, he feels he was rejected by the best firms because he was stigmatized as an Italian-American "greaseball."

Yet unlike many past Italo-American leaders, Cuomo does not speak funny or fit the stereotype of a man with pomaded hair and shiny suits. Unlike Ronald Reagan, Cuomo not only preaches about the virtues of "family" but has an intimacy with his own family. And unlike many liberal Democrats, he has always emphasized the importance of values. Ask many Democrats how they would prevent the rash of teen pregnancies, and they will, ineluctably, advocate more family planning and birth control. Ask Cuomo, as I recently did, and in addition to mentioning contraception he blurted, "Tell them not to have sex!"

The dark side of Cuomo's emphasis on values and loyalty and ethnic pride is that he can be insular. Contributing to this impression is the fact that Cuomo, flirting with a candidacy for president, has few advisors with national campaign experience. His closest advisor is his son, Andrew, a capable and bright man of 28 who sometimes gauges people by whether they were for or against his father in the 1982 race for governor. The danger for Cuomo is that he may learn, as Gary Hart did in 1984, that running for president is not a one-man act. He may also learn that his real political problem is not ethnicity but geography; he is from the insular northeast at a time when the south and west have more electoral votes and are closer to the national political mood.

This concern is related to another, which is that Cuomo is said even by members of his own administration to trust too few people. He is both insulated and isolated, it is widely believed in Albany. Although he works long hours, he spends more time slaving over his own speeches and writing than in meetings with his administrators. Many of Cuomo's supporters were vexed by what appeared to be his impulsive threat to run for president to counter what he referred to as "people talking about, 'An Italian can't do it, a Catholic can't do it.'"

Cuomo explains what happend this way: A New York Times reporter asked him about ethnicity and he answered the question coolly and deliberately. "I didn't explode with Latin passion," he says. "I knew exactly what I was doing." And what he was doing, he explains, was alerting the press and the public to often-unconcious Italo-American biases that were seeping into print -- comparing him to a "godfather," citing his Italian "traits." Cuomo says he is satisfied that his mission was accomplished.

One prominent Cuomo partisan, who believes he would make a good president, nevertheless expresses unease: "As a Jew, I've felt the lash of prejudice. But I don't go around using it as a crutch. I sit in a meeting and I am stunned by his intelligence and sensitivity. Yet I am also stunned by this seeming insecurity."

Which is the real Mario Cuomo -- the man with the bright or the dark sides? Is he principled or obstinate? Intelligent or cute? Inspiring or insular? A luminous or a lousy governor? A moderate pragmatist or a predictable liberal? A new kind of Democrat or a Mondale with verve?

In sizing up Mario Cuomo, it would be a mistake to fall into a familar Washington insider's trap, which is to reduce public figures to a single early snapshot.

Mario Cuomo is a fascinating enigma, a man of many sides and shadows. This truth, however, collides with another: the failure of the press to probe, early on, the character virtues of Ronald Reagan -- or the character defects of Jimmy Carter -- has triggered a backlash.

The small force of political/journalistic moongazers are now straining to capture Mario Cuomo's character in one snapshot. This jostling to capture the inner Cuomo, more than two years before the presidential election, demonstrates that in politics, the new rule is that character counts.