The eight Serbian Orthodox monks at Studenica rise, as has been the custom for centuries, at 4 o'clock in the morning. At 5, as dawn breaks over the secluded monastery's massive stone walls, they file into the King's Chapel to chant mass beneath brilliantly colored frescoes depicting the glories of Serbia's medieval past.

Here, in the rolling hills of eastern Yugoslavia, two very different worlds meet. In the monastery itself, worship is still patterned on the elaborate rituals of the Byzantine court, transferred to Serbia and preserved intact during nearly 500 years of Turkish occupation. Outside is the 20th century in the form of the bureaucratic machinery of a communist state, the artifacts of a consumer society and the changing attitudes of a new generation of young people toward religion.

After some years of considerable tension, both worlds have found ways of tolerating each other's existence. But there is little doubt which now has the upper hand.

In the town of Usce, at the foot of the winding, nine-mile gorge that leads up to Studenica, the local authorities keep a wary eye on the monks -- insisting, for example, that they report in advance the presence of any foreign visitors who wish to stay the night. Monks who visit the town are greeted warmly and respectfully, but their numbers and influence have declined markedly. By day, they become tourist guides, tending to the busloads of sightseers and schoolchildren on outings who troop through the monastery's three churches.

BUT ALL THIS seems irrelevant during the two-hour morning mass. In the confined space of the chapel, all the senses are stimulated simultaneously. The result is a magical alchemy of sound, sight and smell brewed from behind the iconostasis by Abbot Julian in his resplendent gold-embroidered robes.

The monks gather on the right side of the church, standing in strict order of seniority. As the abbot invokes the names of thousands upon thousands of dead believers, they take up the chant. "Gospode Pomiluj, Gospode Pomiluj (Lord have mercy)." Their faces are illuminated by the flickering candles in their hands. Saints and medieval Serbian kings gaze down from the walls of the church as light plays with darkness in a hundred different variations. An odor of incense hangs in the early morning air, blending with the smell of burning wax.

After mass, Abbot Julian -- a refined, almost Tolstoyan figure who, at the age of over 70, still likes to ride over the surrounding countryside on his horse -- presides over breakfast in the refectory. Everybody who attended the service is invited to sit down to a meal of heavy corn porridge mixed with goat's cheese. In the huge kitchen next door, weather-worn peasants gather in the warmth, watching preparations for a huge feast of lamb and suckling pig to celebrate the monastery's saint's day.

The monks say they realize their way of life is threatened and recognize the government's right to take an interest in the monasteries.

"We have nothing against the government preserving historic monuments like ours. All that we insist is that the monasteries should be looked after by educated and cultured people who respect the past," says one monk as he proudly shows visitors the marvelous 13th century frescoes that recently have been restored with government help.

During the day, when not looking after tourists, the monks work on their farm. They are a self-sufficient community, producing virtually everything they need with the exception of sugar and oil. At one time, the monastery owned huge tracts of land, but it is now restricted to 50 acres. Several years ago, the monks were persuaded to modernize their farming methods and now use tractors and harvesters in the fields.

A MONASTERY like Studenica embodies Serbia's history. It was here that the medieval Serbian kings were crowned, here that Serbia's peasant population found shelter against the Turks, and here that the idea of Serbian nationhood was kept alive through centuries of oppression.

In the 19th century, the Serbs became the first of the South Slav peoples to rise up against foreign occupation. Apart from the tiny Serbinhabited principality of Montenegro, Serbia was the first independent Slavic state in the Balkans. When Yugoslavia -- or the land of the South Slavs -- was first formed in 1918, the Serbs were both politically and numerically dominant.

Today Yugoslavia is a multinational federal state and Serbia is just one of six republics. The Serbs exercise much less power than they used to. Given the susceptibilities of the other Yugoslav nations, this is really the only feasible way of running the country. But it has left a residue of resentment in Serbia.

The feelings of frustration among some Serbs were, expressed in a controversial poem by a prominent writer and former communist partisan, Tanasijer Mladenovic: "Serbia, poor and wretched . . . will you be able, as in times past, to renew your strength with a sudden crack? Or will you, discouraged and feeble, disappear among the mountains and nations . . . torn to pieces by apocalyptic forces?"

Mladenovic's poem was immediately condemned as "nationalistic" by Yugoslav officials when it was first published several years ago. But it was taken up by Serb emigre groups, and the kind of defensive nationalism it reflects could be important for Yugoslavia's future.

IN THE SAME way as Serbia's influence has declined, so has that of the Serbian Orthodox Church. Traditionally, Serbs were distinguished from other South Slav peoples by their religion. Church and State were regarded as two sides of the same coin. When a new communist state was formed after World War II, the church's position automatically weakened.

Orthodox customs have, however, persisted -- even if they have lost much of their original religious significance. Most Serbian families still celebrate their annual slava, three days of feasting marking the conversion to Christianity of their early ancestors.

An invitation to attend a recent village slava provided a unique opportunity to witness how, in Serbia, the past lives on through stories and myths. Fueled by a potent drink called Shumadinski Tea (hot brandy), conversation quickly turned to how the Serbs had outwitted all the other nations in the Balkans -- indeed, Europe itself.

A 70-year-old peasant wearing a communist partisan decoration next to a royalist star boasted that "our Emperor Dushan ruled right up to the gates of Constantinople." For him, the fact that the emperor in question lived six centuries ago was unimportant: he quickly went on to describe how with his own hands he had killed five Germans during World War II.

Next door, in a room decorated with modern furniture, the young people of the village gathered with their friends. Sipping whiskey and listening to pop music, they talked about sports and the foreign countries they had visited -- Greece, Turkey and Italy. A portrait of President Tito hung on the walls, and they were rather self-conscious about joining in the elaborate ritual of the slava celebrations.

Later, a visitor remarked to his Serbian companion that the scene reflected the two completely different worlds into which the country is divided. "Yes, it's true," replied the Serb, "but when these people get older and have families, they too will celebrate the slava."

A SMALL INCIDENT at Studenica monastery illustrated much the same point. A recent entry in the visitor's book reads: "If I could choose where to die, it would be in this beautiful place." It was signed by Milovan Djilas.

As a militantly atheistic communist leader, Djilas was closely involved in the antireligious campagin of the late 1940s, when many churches and monasteries were forcibly closed. The monks of Studenica certainly have no reason to feel kindly toward him. But it is interesting that he should have changed his mind about them.