LATE ONE NIGHT, a man in Beirut called a taxi to take him to his girlfriend's village in the nearby Chouf Mountains. The driver refused to make the trip. "That's a Druze village and I'm a Maronite. They'll kill me," he said.

The incident sounds as fresh as today's Lebanon, but it comes from a late 1920s French novel, "La Chatelaine Du Liban." Sectarian strife is deeply embedded in the fabric of Lebanon's bloodthirsty, largely feudal society.

This is something most Lebanese prefer to forget, recalling instead the periods of uneasy truce between the country's 17 different religious sects when Lebanon was called -- perhaps unjustifiably -- "the Switzerland of the Middle East."

Exacerbating the ethnic differences are massive social, political and economic inequities intensified during 19 months of civil war that ended when Syrian troops, under the rubric of an Arab deterrent force, marched into Beirut in November 1976.

Now it appears the old unsettled issues have ignited a new civil war, the third in 25 years, with U.S. Marines and Reagan administration policies caught between the two fundamental facts that govern Lebanese behavior: blood feuds and strong religious hatred; and the unequal distribution of money and power that puts the minority Maronite Christians in control of the country.

The Israelis learned the bitter lesson of the Lebanese quagmire the hard way. After taking what they considered an unacceptable number of casualties they now have pulled back, leaving the Lebanese factions to fight over their positions.

Lebanese love to blame outside forces for their troubles. For many Lebanese, the presence of a Palestinian state-within-a-state caused the last civil war, which began when Maronite Christians ambushed a busload of Palestinians returning from a funeral on April 13, 1975.

"Peace is impossible because of the Palestinians," a young Maronite fighter told me in November 1976 as Syrian troops marched into Beirut.

Like many others, the young Maronite ignored the underlying social, economic and political inequities which were more responsible for the civil war than the Palestinians. To mention those issues then brought a typical Lebanese clucking of tongue against closed teeth as if to say, "You just don't understand."

Now the Palestinians are gone, but Lebanese Moslems and Druze still are fighting Maronite Christians -- as they have for more than a century.

The feudal character of Lebanese society goes beyond religion. For example, the Franjieh clan of Maronite Christians is engaged in a vendetta with another Maronite family, the Gemayels, over the assassination of Tony Franjieh, the son of a former president, and his wife and daughter, by henchmen of Beshir Gemayel, who in turn was assassinated in a bomb explosion just after he was elected president last year.

It seems hard to imagine how the Lebanese can ignore the significance of their internal blood feuds, which are tearing their country apart. But given their ability to sublimate reality, they probably will. Only an honest accounting by the Lebanese themselves could prevent what now appears to be the inevitable partition of Lebanon. President Amin Gemayel, who took over after his brother Beshir's death, made a stab at this recently when he acknowledged that Lebanon's problems lie within its own psyche.

"In reality," he said, "Lebanon is living divided in itself. The time has come to work together."

But the country is governed by an outdated, 40-year-old "national convent" that guarantees the Maronites' predominance. This old compact gives lesser roles to Sunni and Shiite Moslems, and nothing at all the Druze, a breakaway Moslem sect.

The Maronites also dominate the Lebanese economy. There are, to be sure, very rich Moslems and poor Christians. But the poorest of the poor are the Shiite Moslems, who also have the least political clout though they are the majority sect.

This compact stems from a dubious 1932 census that showed the Maronites formed a majority of the country. They have not allowed another head count since. But Moslems are less willing to accept Maronite hegemony as they have become steadily better educated and more willing to challenge the Christians. And now they are a clear majority of the population.

The real question is whether Gemayel is strong enough to force his fellow Maronite Christians to share power with the Moslems. At the moment he appears too weak to do so. He may control the Lebanese army, but the Israeli-trained and equipped militia of his Phalange Party, the most powerful armed force in the country, pays little attention to President Gemayel.

The Maronites, moreover, feel they must control the country to protect their archaic brand of Christianity from being swamped by the sea of Islam all around them. They believe they are descendants of the Phoenicians and the only true Lebanese. The various Moslem sects clearly disagree. The new civil war has placed Druze warlord Walid Jumblatt in an uneasy alliance with Syria to protect his tribe from the Christians.

So today's fighting reflects both traditional sectarianism and a continuation of Moslem and Druze struggles to gain a larger measure of control over their country. But this time the very existence of Lebanon hangs in the balance, and the major Western powers have been dragged into the fight as well.

The Reagan administration appears to hope that Gemayel will somehow be able to overcome Lebanese history and gain control over the entire country. But Gemayel has not even been able to control the capital city, where U.S. Marines are being killed by Druze artillery firing from nearby mountain hideaways.

And this time, the superpowers are involved. Not far from the American Marines in Beirut, Soviet "advisors" now man Syrian anti-aircraft batteries in the eastern Bekaa Valley.