In the squalid shantytowns that dot the Chilean capital of Santiago, particularly along the northern and western edges of the city, the acrid odor of burning tires mixes with the hovering stench of tear gas. Police and residents scuffle almost daily. At night, the wailing sirens of the police wagons make sleep difficult.
But in the more affluent neighborhoods on the western rim of the sprawling city, middle- and upper-class Chileans sleep peacefully, far removed from the tumultuous confrontations in other parts of their city. Many are blissfully unaware of what is going on in the shantytowns.
There is a surrealistic touch to it all.
''It is hard, even for us Chileans, to understand,'' comments Sergio Bitar, a Socialist leader who recently returned to Chile from several years' exile. ''Actually, when you analyze things, you realize Chile is at least two and maybe several countries in one. One is the country of General Pinochet and the other is the country of those who are poor, repressed, and without opportunity.''
Radomiro Tomic Romero, a longtime Christian Democratic politician, goes further: ''It has been this way for as long as anyone can remember. There's the Chile of the poor who survive on precious little, and then there's the Chile of the middle and upper classes who live very well. They do not mix.''
Mr. Bitar adds that ''the two Chiles simply are at opposite polls. We are, in short, a polarized society.''
Although their analyses may sound oversimplified, Bitar's and Tomic's comments, corroborated by numerous other observers, help to explain the political and social turmoil gripping the South American nation. They suggest the reasons that Chile's strong man, Augusto Pinochet Ugarte, has been able to hold on to power for more than 11 years through steady opposition protests.
Another prominent Christian Democratic leader who has been closely involved with the protest movement sweeping the shantytowns in recent months says that Pinochet remains in power because so many Chileans are content with their lot. He spells it out:
''They lead comfortable, pleasant, middle-class lives, are vigorously opposed to Marxism, and recall what Chile was like before Pinochet came to power, and simply do not want to do anything that would threaten the current order of things.
''If they would reflect deeply on what Pinochet is doing, I am sure many of them would not be at all happy. After all, we are a democratic people.''
As Chile rocks from one clash after another between police and protesters, however, it is clear that the demonstrators are not all poor - that some in the large middle-class are involved.
Some Chileans who support the protests are part of the wealthier two-fifths of the population. Some of them, like Gabriel Valdes Subercaseaux, the Christian Democratic leader who was once a respected Chilean foreign minister, are attempting to bridge the gap between the two Chiles.
Many other Christian Democratic leaders (Juan Hamilton, Patricio Aylwin Azocar, and Andres Zaldivar Larrain, for example) and Socialists (including Bitar) are similarly comfortable. Many live in pleasant, albeit not luxurious, homes out along Providencia, a main thoroughfare where many of Santiago's most fashionable shops are located, or in more suburban areas around Apoquindo to the west. But they are among the leaders of the protest movement, and over the years have been instrumental in attempting to ease the plight of the poor.
The Chile of the poor, where the protests against 11 years of military rule are most angry, is a Chile of small, overcrowded wood and adobe shacks along rutted, dirt streets, where more than half of this capital city's 3 million people live. Unemployment among these people is high, in some areas as high as 30 to 40 percent; disease and malnutrition are serious problems; schooling is at best limited; and poverty is a daily worry. The protest is as much against their plight as it is against Pinochet's rule. But the poor have come to view the general's rule as the cause of their continued poverty. Early in the Pinochet years, the general had some support in the shantytowns.
In turn, the Pinochet government now sees the shantytowns as the sites of sedition and antigovernment action. As a result, the shantytowns have been most severely affected by the government's state of siege. Human-rights abuses are legion. Police units regularly sweep through the shantytowns, picking up hundreds for questioning. In turn, shantytown dwellers have taken to burning tires as roadblocks to keep the police out - an action which, in turn, prompts the police to use tear gas and water cannons.
''The situation is turning ugly,'' says Enrique Palet, executive secretary of the Roman Catholic Church's human-rights organization, the Vicariate of Solidarity.
Many other Chileans would say it is likely to get uglier if the gulf that separates the two Chiles is not bridged.