THEY ARRIVED WITH the rain, early on a winter Sunday, while most of Brooklyn slept. First hundreds, then thousands appeared. Pale men with grizzled beards and black fedoras, trailed by wives and surrounded by children.

As always, the line moved silently along the broad pavements of Eastern Parkway and into the cavernous synagogue at the corner of Kingston Avenue. A brilliant red-and-yellow banner snapped in the gusting winds outside the World Lubavitcher Headquarters: "Messiah Is on the Way," it proclaimed in Hebrew and English. "We Want Messiah Now."

For the trembling faithful, here to receive a crisp dollar bill and a blessing from a regal old man in a double-breasted waistcoat, the savior already has a name: Menachem Mendel Schneerson, seventh Rebbe of Lubavitch, the Hasidic oracle of Crown Heights.

"Don't look at his face," a frightened Russian woman, Irina Krenslayka, whispered to her young son as they approached the reclusive, 89-year-old leader of the world's most ambitious, aggressive and, at times, detested Jewish movement. "Don't look at the holy man."

Few do. His burning, electric blue eyes forbid it. Each Sunday, this man powerful enough to divide Jewish leaders in America and to affect the politics of a nation he has never seen dispenses dollars to the devout and the curious. Thousands of each file by for a brief glimpse and perhaps a few words. Two attendants — both rabbis — grab the fresh new bills from shopping bags and stack them on a green, velvet-covered table.

Leaders of commerce stand with beggars; pious Jews with politicians. Bob Dylan one week. The Ambassador from Israel another. Dozens of Israeli Cabinet ministers and Knesset members make the visit a part of any trip to New York. Ancient but erect, the Rebbe never moves until the line has ended. Usually, it takes four hours–sometimes eight.

"Rabbi, my sister is dying." A frail English woman approaches in tears. "I feel so alone. Please help." The Rebbe hands her an extra dollar and reminds her to give both to charity. She thanks him as a woman pushes her through the doorway and under the oak lintel leading toward the street. The exchange, unusual in its length, lasts nearly a minute.

No question of human life escapes the dollar line. Desperate, infertile women plead for special prayers. There are men who want permission to leave their wives and others who have lost their luck in business. "I'd like to know my purpose," one woman asks. "I need a new car," says another.

The Rebbe, a dynastic title bestowed upon the chief rabbi, or leader, of a Hasidic sect, responds to all — mostly in Yiddish, but often in English, French, Russian or German — with brusque wishes for good news and the dollar. Many of his visitors, however, bypass the charity box mounted on a nearby wall and instead race to the street, where enterprising Russian immigrants wait to laminate them, melting the Rebbe's stern, fatherly portrait over the benign face of George Washington.

"He looked at me and my life just changed," said Ron Garonce, a photographer from Montreal. He has come to Crown Heights for the weekend to attend a conference the Lubavitchers often hold for the less observant Jews they seek to bring to their version of Orthodoxy. "For an instant his eye caught my eye. How can I describe what that's like? You know on 'Star Trek' when they beam you up? That was what it was for me. He caught me from my toes to my eyes, and he beamed me to a truer level of Judaism."

GRAFTING THE 18TH CENTURY onto the 21st, driven equally by medieval doctrine and modern technology, Menachem Mendel Schneerson presides over an empire of Jewish mysticism that stretches from the alleys of Brooklyn to the Himalayas. A virtual hermit, Schneerson is the first leader of any ultra-Orthodox movement to pursue the redemption of secular, wayward Jews. He has waged vigorous, unending war against assimilation — the central trend of modern Jewish life — which his followers never hesitate to describe as "a spiritual holocaust."

Few who have encountered it can forget the Lubavitchers' singular brand of audacious, in-your-face Judaism. Alone among the Orthodox, they seem to be everywhere. In the 42 years since he took over, the Rebbe has unleashed thousands of zealous emissaries — from Norman, Okla., to Dar es Salaam, Tanzania. Laden with religious supplies and information for any Jew who will listen, his mitzvah tanks patrol the Lower East Side and the Golan Heights. The Lubavitchers' Brooklyn-based publishing house has become the largest distributor of Jewish books in the world, and their telephone hot lines and newscasts operate 24 hours a day.

Lionized by his nearly 200,000 followers and despised with equal intensity by his many detractors, the Rebbe knows that even his briefest remark is capable of shaking the foundations of Israel, and of modern Jewish life.

As he has done several times before, the Rebbe helped set off a small crisis in Israel this winter — just as peace talks began to intensify. With a brief comment to the visiting Israeli Transport Minister Moshe Katzav, he sent Prime Minister Yitzhak Shamir a sharp, unequivocal message about trading land for peace.

"It is an abomination," the Rebbe said, "even to think about discussing autonomy for the Palestinians." Reported widely by the Israeli press, the warning was heard by Shamir — and by his opponents.

"The power of this old man in Brooklyn, who passes himself off as the Messiah, is indecent and insufferable," says Yossi Sarid, an opposition member of the Israeli Parliament. "There is no parallel anywhere in the world. Even worse are the Cabinet ministers and the members of Knesset who make pilgrimages to him, abase themselves before him and thirstily drink his worthless utterances."

The Rebbe doesn't grant interviews — to the press or anyone else. Despite pleas from religious and secular leaders, he never commented on the riots and despair that shook New York last summer when a car escorting him from a visit to the graves of his wife and father-in-law killed a black boy, setting off days of racial violence. He and a trusted adviser make the short trip in his gray Cadillac Brougham at least once a week — to commune with the soul of his father-in-law, the last Rebbe. Except for those journeys to the cemetery in Queens, and a quick visit to his followers at a Hasidic summer camp in the Catskills in 1957, he has not left Crown Heights in 44 years.

Immobility has hardly dulled his influence, though. Like the writings of Chairman Mao during the Cultural Revolution, the Rebbe's most common thoughts are treated by followers as if they were blazing prophecies. When one of the Lubavitcher Hasidim calls or greets another, he doesn't say hello; he often asks, "Any news from the Rebbe?"

His "news" comes largely in rambling Yiddish talks after prayers, or when visitors are able to corner him for a moment in the labyrinthine hallways of the three-story Lubavitcher headquarters at 770 Eastern Parkway ("770" is all anyone ever calls it, like Number 10 on Downing Street) — as he returns to the single ground-floor room in which he spends his life. The oak-paneled chamber contains a narrow cot, hundreds of Hebrew books, Hasidic texts and other volumes essential to Jewish learning. There is a hand-tooled mahogany desk for writing and a radio on which he listens to the news and occasional Yiddish broadcasts. In one corner of the room, he keeps filing cards with the Hebrew names of thousands of those who have written to him over the years.

Crowds frequently gather outside the room before and after prayers to chant and cheer the Rebbe on. It was in a similar encounter several years ago that the Rebbe told the American cosmetics heir Ronald S. Lauder that no philanthropy should be wasted on Poland. "It is not a fit place for Jews to live," he said. "All who can should leave."

Except on the Sabbath, when recording is forbidden, nearly every word the Rebbe speaks is taped and then ferried across the world on the Lubavitcher satellite television network. His Sabbath talks — informal, Talmudic disquisitions that run for hours — are reconstructed by scribes and faxed to disciples at the outposts of empire the minute the sun sets.

"If it were not labeled Jewish, you would say it is a cult," says Rabbi Avraham Ravitz, the head of Israel's Degel HaTorah Party, which was established by the Rebbe's most outspoken adversary, 93-year-old Rabbi Eliezer Shach. "The Rebbe has great influence, and his movement has many followers. But it is a strain on Judaism and a strain on Israel."

AS HE APPROACHES HIS 90th birthday next month, the Rebbe's power has never been greater. A Sorbonne-educated engineer who spent part of his youth in the cafes of Berlin, he has transformed a withered, demoralized movement almost obliterated by the Holocaust into a missionary juggernaut. In the process, he has achieved a status unlike that of any Jewish leader in the world.

Born on April 14, 1902, in Russia, he is the seventh in the dynastic lineage of Lubavitcher leaders who take their name from the Russian town near Poland where the movement began in the 18th century. Hasidism, grounded in mysticism and emotion, grew as a democratic reaction to the Eastern European convention of limiting Talmudic study to intellectuals. The movement stressed the essential importance of prayer for all Jews, and it organized in communities around powerful leaders or teachers, called Rebbes. Lubavitcher legend has it that this Rebbe, a direct descendant of the founders, was so brilliant in school that his father, Rabbi Levi Yitzchak Schneerson, a Talmudic scholar, had to remove him from class and hire a tutor.

He spent his teen-age life immersed in the Torah, and in 1929 he married the second daughter of the sixth Lubavitcher Rebbe. Both Schneerson and his wife, Chaya Moussia, who died in 1988, are great-great-grandchildren of the third Lubavitcher Rebbe, his namesake, Rabbi Menachem Mendel of Lubavitch. Hasidic leaders are not chosen like monarchs; children of Rebbes do not automatically become Rebbes themselves.

The Rebbe spent the 1930's in Berlin and Paris, studying math and engineering before immigrating to the United States in 1941. "He was really a typical highbrow — a true intellectual," says Rabbi Adin Steinsaltz, one of the world's foremost Talmudic scholars and perhaps Israel's most distinguished adherent of Lubavitcher Hasidism. "He would sit for hours and discuss subtle points of religion and science."

The Rebbe was not exactly a member of cafe society, Rabbi Steinsaltz hastens to add. But coming from a world where Orthodox Jewish scholars rarely thought about secular affairs and many never even visited a university, the fact that the Rebbe read Proust and Hegel made him seem comparatively like a wild man.

"No other Jewish leader has tasted the world in that way," Steinsaltz says. "When you examine his achievement, it is almost unbelievable. In 40 years, he has created from nothing a new experience for Judaism."

In a society where families often have 8 to 10 children, the Rebbe and his wife produced none. But despite his age, the scare of a heart attack nearly 15 years ago and a mild stroke suffered at his father-in-law's grave early this month, his loyalists refuse even to contemplate what will happen when he dies. After news of his illness spread throughout Israel last week, thousands of his most ardent disciples streamed into Jerusalem to pray for his health. No mechanism to replace him has been established, no candidates discussed.

"There never has been any consideration of that subject," Rabbi Yehuda Krinsky, one of the Rebbe's closest confidants, said after the stroke. "It isn't necessary."

"Messiah will come," Lubavitcher leaders and educators say over and over in answer to questions about the succession to the top of the world's largest and most influential Hasidic organization. "It simply isn't a problem."

The Rebbe has never blatantly encouraged the Messianic fervor that swirls constantly around him. But neither has he dissuaded the faithful. He has frequently cited recent world events — the collapse of the Russian empire, the mass Jewish exodus to Israel, the forceful defeat of Iraq and the enormous airlift of Ethiopian Jews — as signs that the Messiah is on the way.

His picture hangs in virtually every Lubavitcher living room in Crown Heights — and in taxis, falafel shops and groceries from Flatbush to Jerusalem. When Israeli soldiers ride into battle, they sometimes leave with a picture of the Rebbe by their side. At Judaica World, around the corner from 770, thousands of such pictures are for sale: in frames, on keychains, as posters, calendars and wallet-size keepsakes.

Asked recently if he had any message for his followers in Israel, who have built in the rural olive fields not far from Tel Aviv an eerily exact replica of his headquarters — complete with iron window gratings and American-made Schlage locks — the Rebbe didn't hesitate. "Tell them Messiah is coming very soon," he said. "They must be prepared to accept him properly."

SEVERAL HUNDRED MEN and women, comfortably dressed in tweeds and silk, are jammed into the huge main hall of the Brooklyn Jewish Center on Eastern Parkway. Heavy damask curtains ring the room, and a plentiful kosher buffet has been provided.

There are no black hats or somber caftans here. The meeting, organized by Lubavitcher leaders, is aimed specifically at the majority of Jews who are not Orthodox. Many of the guests today have spent the weekend in the neighborhood — welcomed warmly into Hasidic homes for the Sabbath; others are here for breakfast, and to listen to a talk by Rabbi Manis Friedman, the slick, almost hip young dean of the Bais Chana Women's Institute of Jewish Studies in St. Paul and one of the Rebbe's rising superstars.

Eloquent and witty, Friedman and others like him throughout the world slide a velvet glove over the iron fist of Lubavitcher dogma. This morning, he will encourage visitors to accept their status as "the chosen," and to understand its burdens. It is all part of the central Lubavitcher paradox: other Hasidic sects — like the Satmar, based in the Williamsburg section of Brooklyn, and the Bobov in Borough Park — withdraw from the world; Lubavitchers reach out. But while they embrace Jews, they remain strikingly unwilling to accept their diversity.

To the Rebbe and his followers, interfaith marriages simply don't exist; Reform and Conservative rabbis have no standing, and Halakha — Jewish law — stands far above any other. That means religious conversions and other ceremonies performed by Reform or Conservative Rabbis are worthless.

"It's foolish to talk about labels for Jews," says Rabbi Krinsky, the movement's glib, energetic chief spokesman, who keeps a map with the estimated Jewish populations of 173 major cities in the United States and Canada on his wall. Red pins mark cities with Lubavitcher centers. "Labels separate us. We choose to talk about what brings us together."

But the divisions are hard to ignore. Lubavitchers see only two kinds of Jew: those who are fully devout Lubavitchers and those who someday may be.

Today Rabbi Friedman is on the prowl for the latter. Looking like a funky college professor in his long gray beard and tattered cardigan, he wastes no time telling the crowd he has come on serious business. "Wake up," he says. "Jews are different. Let's accept it and be thrilled."

At first, the group seems thrown by his candor. "For 2,000 years we have denied our uniqueness," he tells them, speaking gently into a microphone. "We have tried to come to the world as if we were normal. Well, guess what? The world hasn't bought it, and they never will.

"Millions of Jews who are so uncomfortable with who they are have tried very hard to be like the others," he continues, a little louder, pulling the crowd to him. "It will never happen. We have packaged it a million ways and it has never worked. So why not tell people who we are? Tell them we are chosen. When the Jews act chosen, the world loves it. We are the seat, the repository of God's will. But we have been so intimidated by 2,000 years of exile that we no longer have the courage of our convictions."

He stops for effect, sensing the power of his words rippling through the crowd. Then he tosses out a Jewish joke. "Two Jews are standing in front of a firing squad," he begins, his eyes crinkling with delight. "They are going to die. The countdown begins — 10, 9, 8, 7, 6 — it's all going according to plan."

He stops again, to drink some water. "Finally, when the number hits 4, one of the men starts wailing a fierce Hebrew prayer to God. The other turns in horror and shouts, 'Shut up, you fool, or you'll get us in trouble.' "

Rabbi Friedman waits a few seconds for the joke and its message to soak into the assembly. "The pathological need for silence and approval," he declares, shaking his head. "Those days are gone. We are different, and we must show it. The only authority the world will accept is a Jew that speaks in the name of Torah."

This is hard-core stuff, a soulful presentation of the movement's internationale. And while few of this day's visitors will renounce their current lives and become full-fledged Hasidim, the success of these efforts cannot be questioned. There may be at most 200,000 Lubavitchers in the world, according to scholars who study the sketchy demography of modern Judaism. But according to both admirers and detractors, the movement's sympathizers and financial supporters– among secular Jews — run into the millions.

"It's grass-roots Judaism," says Rabbi Dovid Eliezrie, director of a Lubavitcher center in suburban Orange County, Calif. "The numbers are impossible to count. Do you include just those who wear black hats, or also those who keep kosher? How about the ones who go to our Hebrew schools but play Little League baseball on the Sabbath? You have to look at who we touch. We may not be at the inner councils of American Jewish bureaucracy, but you have to see us as a major player in Jewish life."

The contradictions hardly seem to matter. Though strident and inflexible in their opposition to the Judaism that most American Jews practice, the Lubavitchers have been astonishingly adept at getting them to contribute millions of dollars to their cause. Because they receive religious exemptions from many income-tax filings, there is no clear gauge of how much money they raise each year to support their growing international network of 1,350 yeshivas, nonsectarian drug-rehabilitation clinics, summer camps, synagogues and meeting houses. But Rabbi Krinsky says $100 million is guessing on the light side. And all experts agree the bulk of that money comes from Jews who are not Orthodox.

"They play to nostalgia better than any other religious group," says Allan Nadler, a former rabbi of the largest synagogue in Montreal and now director of research at YIVO, the Jewish Scientific Research Institute in New York. "People see them as the real Jews, like their grandparents. They see what they are not. Lubavitchers play to this penetrating sense of guilt and inadequacy many modern Jews have. In some strange way, they think giving them money helps support what their ancestors were. It's a lie, but it makes them feel better."

The Lubavitcher movement, also called Habad, an acronym for the Hebrew words for wisdom, understanding and knowledge, has struggled to straddle the ultra-Orthodox world of Hasidism and the modern world in which the Rebbe was educated. Other Hasidic groups have contempt for their willingness to engage in the world. Yet mainstream Jewish organizations have at times displayed even greater revulsion for their fundamentalist views.

"The minute you reach out like they do you compromise yourself," says Samuel C. Heilman, a professor of sociology at Queens College and the author of "Defenders of the Faith," a new book on Orthodox Jews. "The Rebbe saw — as nobody ever did before — that to succeed in the United States you have to speak out. But this is a closed, restrictive society. To the other Hasidim, he has ventured too far. For most Americans, however, he remains a fanatic fundamentalist. The stress there is obvious."

The tension has never been clearer than in 1988, when after 20 years of trying, the Rebbe split the Jewish world, by nearly succeeding in forcing Israel's Law of Return to require that all who convert to Judaism do so under traditional Orthodoxy. In Israel, the change could have invalidated the central beliefs of most American Jews.

Less than two weeks before the elections — after years of saying Habad was not political — the Rebbe instructed thousands of his Habad followers in Israel to get out the vote for a small, insignificant ultra-Orthodox party known as Agudat Israel. When it was all over, Agudat won five seats in the Knesset, far more than anyone had predicted.

The votes, along with those of another small ultra-Orthodox party, Shas, were enough to swing the balance of power between the country's two major parties. And as soon as he agreed to accept the Rebbe's views on the Law of Return, Prime Minister Yitzhak Shamir won the endorsement of both Orthodox parties. In the end, the measure failed, but Lubavitcher and other Orthodox leaders in Israel say they will try again as soon as the political opportunity presents itself.

"It was the most serious crisis between American and Israeli Jews since the founding of the state of Israel," says Rabbi Eric H. Yoffie, vice president of the Union of American Hebrew Congregations, the nation's umbrella group of reform congregations, which worked furiously to derail the initiative. "And it was an issue in Jewish life only because of the Rebbe. It was his obsession. He turned the Jewish world on its head, and it is hard to know if Israel has recovered."

MANY SMALL villages dot the highway on the dusty Mediterranean plain between Jerusalem and Tel Aviv. Olive trees and lemon groves guide visitors to an access road not far from Ben Gurion Airport. From there, it's only a short dash in Berke Wolf's battered old blue Volvo to 770 — the Israeli edition. Standing alone in the middle of the sun-drenched rocks, the familiar red-brick structure with the peaked gables sticks out like a Hasid at High Mass.

"The Rebbe wanted a building here," Wolf says, explaining the construction in Kfar Habad of a replica of Lubavitcher's World Headquarters so exact that even the shelves where Brooklyn yeshiva boys collect their mail have been duplicated. "Why not make something familiar?"

Familiar to whom, people have often asked. Certainly not the Rebbe, who has never been to the thriving Lubavitcher village of Kfar Habad, or to the holy city of Jerusalem, or to Israel itself. His tiny, oak-paneled room is ready for him, and there is a special chair — just like the richly upholstered red velvet seat he uses at prayers in Brooklyn — waiting for his arrival.

Yet even Wolf, the Rebbe's bearlike, militantly loyal Israeli point man, has his doubts. "I would very much love him to come here someday," he says, as he strolls through the peaceful town of 6,000 where every building — the new million-dollar ritual mikvah bathing pool, the day-care center, the sports complex, the Isaac and Haya Gilinksi School of Engineering — display commanding pictures of the Rebbe. "I don't know if he will come before Messiah. Then I know he will come for sure."

There are a hundred reasons given for the Rebbe's eternal absence from the Promised Land: The Torah suggests that those who enter should stay; the Rebbe's 30,000 followers in Crown Heights need him more than Israel does; his distaste for a secular Government in Zion prevents him from entering the land. (He, at least, acknowledges the Israeli Government. Other, more militant religious groups refuse to pay taxes to the ungodly secular state, and some don sackcloth and fly black flags from their windows on Israeli national holidays.)

"Nobody really, really, really knows why the Rebbe has never gone," says his confidant, Rabbi Krinsky, who himself has not been to Israel in 34 years. "He has reasons for everything he does. So when the time is right, he will go."

Habad's preoccupation with messianism has infuriated many Israelis, who throughout history have known too well the searing pain of obedience to false prophets. The Rebbe's followers dance around their devotion. They never actually come out and say he is the Messiah, but Wolf's answer sounds like the one given by Rabbi Krinsky in Brooklyn or dozens of others who were asked whether the Rebbe is the Messiah.

"Judaism teaches that Messiah is a man," Wolf says through a translator in Yiddish. "He won't arrive in a clap of thunder from heaven. Every generation has its candidate, and, of course, in ours, no man has the brains, the ability, the talent and the achievements of the Rebbe."

Perhaps, too, no one else has his support. True believers long for the Rebbe's presence in his house at Kfar Habad in the same way that they long for a world of perfect wonder.

The Messiah, they believe, can come at any moment. When devout Lubavitcher children go to sleep at night, they sometimes put their best clothes next to them, so they will be well prepared if the Messiah wakes them. Followers are even said to carry beepers so they can learn immediately when the Messiah arrives. Rabbi Moshe Herson, dean of the Rabbinical College of America, a Lubavitcher undergraduate yeshiva in Morristown, N.J., describes the Messiah's imminent arrival as "the fact that puts all others in perspective." And recently, the International Lubavitcher Women's Organization advertised a Torah study meeting this way: "We are living in an extraordinary time . . . in the time of the Messiah. We, the Jewish women of this generation, have the responsibility and merit to lead the way in welcoming our righteous Messiah."

To many Jews in Israel, this is all a bit too much. Before the Rebbe flexed his political muscle with the Law of Return issue, Israelis usually viewed Habad as benign: a sort of warm, rustic, "Fiddler on the Roof" reverie of their absent Eastern European elders. But the Habad movement in Israel, with Wolf cradling his car phone as he races in an endless loop around Tel Aviv, Kfar Habad and the back corridors of the Knesset in Jerusalem, has little time for nostalgia.

"It is easy to dismiss them, they only control a couple of seats," Avishai Margalit says dryly. A professor of philosophy at Hebrew University in Jerusalem, he has written widely about the ultra-Orthodox. "But the Rebbe and his men are involved in Israeli politics on a daily basis. And they are often effective. Sometimes that is hard to accept from a man who doesn't live here."

In 1990, two years after the Law of Return crisis, the Rebbe's chief allies in the Knesset, Avraham Verdiger and Eliezer Mizrachi, helped scuttle an attempt by the Labor Party leader, Shimon Peres, to form a government. Both men defected from the Peres coalition after the Rebbe let it be known that he opposed a government that would compromise Israel's control over the occupied territories.

Habad leaders insist that their attachment to Israel is religious, not political — a tough distinction in a country where the two rarely run unmixed, and where their campaign-style bumper stickers — "Messiah: Be a Part of It" — have become nearly ubiquitous. The group's charitable work on behalf of Russian immigrants, the poor and the aged is well known. Habad runs the country's oldest soup kitchen in the heart of Jerusalem's Mea Shearim, a neighborhood so devoted to the haredim — those who tremble, as the ultra-Orthodox are called in Israel — that people caught driving there on the Sabbath have been stoned by residents.

They have also taken to Kfar Habad hundreds of sick Chernobyl children, young Jews who lived near the Soviet nuclear reactor when it exploded — many of whom have become orphans. Habad bears the cost for their education, their medical bills and their living expenses.

"They are everywhere in this society," Margalit says. "You can't judge their impact or their presence or even their goals sometimes. But they are all around."

They are even at the airport. Any traveler passing through customs at Ben Gurion Airport walks past an H. Stern Jewelry concession, a diamond store and a brightly decorated kiosk filled with brochures about Judaism — manned throughout the day by a Lubavitcher rabbi. "Judaism with a smile," it says on the roof. "Welcome to everyone."

STILL, IT IS IN CROWN HEIGHTS where the Lubavitcher welcome is always warmest. Surrounded by extended stretches of New York's most decayed and embattled neighborhoods, the Hasidim pass quiet, self-contained lives on tidy, tree-lined streets.

It is not always easy to do; racial tensions between the relatively affluent Hasidim and the poverty-stricken minorities who predominate in the neighborhood are never far from the surface. Over the years, there have been periodic rumors among the faithful that the Rebbe would order his followers to move outside the city. The closed, deeply ritualized environment of Crown Heights, however, is clearly where he feels most at home. And for the Lubavitchers, everything revolves around the Rebbe.

Lubavitcher families live in the roughly 50-square-block community so they can worship with him, educate their children in the multimillion-dollar Habad yeshivas he created — a new one every other year to accommodate the surge in population — and so they can be near him on the Sabbath and holidays.

It is a hermetic, completely Jewish world. Although most homes have televisions (the Lubavitchers call them monitors) to watch tapes of the Rebbe, few ever turn on commercial programs. Neighborhood living rooms are filled with books — all in Hebrew. When a young boy is asked what he wants to be when he grows up, he answers quickly: "I want to be a carpenter, so I can build the Third Temple."

The First Temple, built by King Solomon, was destroyed in 586 B.C. Of the Second, reconstructed by Herod in 20 B.C., only the Western Wall remains. The completion of the Third Temple, according to Jewish tradition, will herald the age of the Messiah.

Early every Friday afternoon, Eastern Parkway fills with yellow school buses shuttling Lubavitcher men home for Shabbos. As darkness approaches, waves of other men in black felt hats and long coats emerge from the subway station in front of the headquarters. Soon the giant air-raid siren at the corner of Kingston Avenue and Montgomery Street will blast — warning all that sundown is upon them.

Twenty minutes later, the shrill, penetrating sound cuts the air again. Then the outside world stops. Men attend services while their wives prepare the evening meal, and afterwards there is almost always a celebration to attend. "It seems like there is never a day without one," says Shabse Turner, visiting from Chicago one recent Sabbath, to celebrate the birth of a grandson. "You can go from bar mitzvah to wedding to bris. We never want for something to do in an evening."

Tonight it is the shalom zachar ("welcome to the boy" in Hebrew) of his grandson, the new son of Betzalel Lesches and his wife, Michal. It was a particularly good week in Crown Heights: six boys were born. Their names are announced at the synagogue at 770 and, as is customary, their births are celebrated on Friday after services. Nobody knows how many girls were born. They don't keep count.

"No, you don't see anybody celebrating our arrival," says Devorah Krinsky, the Rabbi's wife, as she serves an elaborate and beautifully prepared meal that she made before the sun set. "We're just here to do the work."

She means the snappish comment as a joke, at least in part. She is clearly eager to mount the spindly old stairs to the Lesches' fourth-floor apartment to join in welcoming their latest son. Except for the Coke bottles and paper plates, the scene might be frozen from a party given in the 18th century. Twenty-three men, all in black hats and somber suits, sit in the dining room. They drink Scotch from thimble-size glasses as they pass huge plates of cakes, cookies and candies back and forth. A single fluorescent light bathes their pallid faces. The women congregate in the kitchen, laughing and discussing the week's news.

On the street outside, knots of men gather to trade gossip and talk about their workweek — in Manhattan's diamond center, in the garment district or as lawyers, doctors and shopkeepers nearby in Brooklyn. Driving is forbidden on the Sabbath. So it is customary for groups to walk together from the synagogue to the homes of friends and relatives. It is another reason to live close to the Rebbe.

The big event of the week comes on Saturday. After morning services and a quick meal, thousands of people scurry back to the aging, dilapidated basement at 770 that serves as the main Lubavitcher synagogue. At least 3,000 men cram themselves into a human arc surrounding a long table stretched across a wooden platform. Elegantly dressed women, their noses pressed against tinted Plexiglas windows, sit in a balcony above. This is the farbrengen (Yiddish for get-together or gathering). It is a chance for the Rebbe to expound in an informal way on Torah study or weekly events.

By 2 P.M., when the Rebbe is scheduled to appear, the room has become so steamy on one of the coldest days of winter that air-conditioning is required. It doesn't help. The air is stale with sweat. Two brief fights break out, among men crushed together like cattle. Occasionally, people in the crowd lose their balance, carrying hundreds of others in a huge wave that looks like cascading dominoes.

Finally, the Rebbe strides into the room. He takes his chair at the center of the table and begins to talk. He speaks in Yiddish about the painful lessons of Jewish exile, and as is frequently the case, about redemption.

"The ultimate redemption of our people and of the world at large is not a remote promise," he says in a whisper that silences even the children in the room. Because it is the Sabbath, no microphones can be used. Teen-agers take turns standing on one another's shoulders; one man holds an ivory horn to his right ear to help funnel the sound.

"The Jews of our generation have been granted complete atonement and are now at the highest pinnacle ever of our national history," the Rebbe continues. "All the divine service necessary to bring about the redemption has been completed."

By the end, three hours later, the Hasidim are waving, chanting wordless Hebrew melodies, passing jugs of kosher wine and toasting the Rebbe. For a while he sits impassively. Then, like an aging orchestra conductor, he rises, waves his arms wildly and brings the crowd to a frenzied crescendo.

"This is what we live for," says Rabbi Benjamin Klein, a sweet, sad-eyed attendant of the Rebbe. "Can you think of anything better?"

ANOTHER SABBATH HAS arrived, and the sunlight begins to fade from the Old City of Jerusalem. The muezzins have already called the Muslim faithful to prayer at the Dome of the Rock. Nearby, hundreds of Jewish pilgrims have also begun to gather at the unadorned stone face of the Western Wall, the last vestige of the Second Temple. Its rugged surface is the most sacred place in Judaism.

Thousands come to the wall every day. Many stick slips of paper with their most fervent wishes into the crevices between the stones; others put on tefillin — the tiny containers of holy scripture that are worn near the head and the heart to show dedication to God. Lubavitchers have made it a special goal to convince as many Jewish men as possible to wear the tefillin, and they consider it a mitzvah, or gift, to wear it at the wall.

As young men approach, many wrap the leather straps attached to the tefillin around their arms, repeating the special prayer for the purpose. Some snap each other's picture, as if they were at the Eiffel Tower or Big Ben.

From a corner, near a stone passageway, two devoted Lubavitchers watch carefully, summoning a stranger.

"Are you Jewish?" Mordechai Scheiner, a transplanted New Yorker, asks. "Shabbos is coming. You should put on tefillin."

To Scheiner's amazement, the visitor declines. "This is important," he continues, pleading. "You should do it. Do it for the Rebbe if you don't want to do it for yourself or do it for me."

"Why?" asks the stranger. "What is the point?"

"The point?" he replies. "The point. Does there have to be a point? O.K. Here's the point. Did you ever buy a lottery ticket? Sometimes you win something. Sometimes you win the grand prize. Well, when Messiah comes you can't win if you haven't worn tefillin. Think about it."