World heritage: from Da Vinci to the white rhino.

On the last days of the eighteenth century, a merchant in France bought Europe's largest Romanesque church for a ridiculously small amount of money. He then proceeded to tear it down and sell it, piece by piece. There was no public outcry. The idea of such a symbol of a national-let alone, universal-heritage made of brick, wood or stone was alien in the Age of the Enlightenment, when people were still struggling to digest the recently introduced notion of a universal literary heritage.

It was only after the ravages of the Second World War that a radical and original concept began to capture the imagination of people everywhere: that of a universal cultural and natural heritage.

It meant that certain buildings, objects and environments had to be preserved because they were crucial, tangible evidence of the past, or expressed the essence of a civilization's unique creativity and offered clues for its renewal and future. Or, in fact, were, simply, beautiful. Modest or grandiose, they were all irreplaceable. Their loss would impoverish us all. A brutal test

For 20 years, UNESCO elaborated and promoted the concept. Then, in 1960, it

was brutally put to the test. The precious monuments of the Nile valley were condemned to be submerged beneath the rising waters from the Aswan High Dam. Egypt's economy desperately needed the dam. And, for a moment, it seemed that survival for the living required the destruction of their own history.

But the whole world was mobilized, arguing that it had a right to preserve those monuments. UNESCO launched an international campaign. And with Egypt's full co-operation, archaeologists explored the threatened sites and 22 temples were dismantled and rebuilt on safe ground. The huge complexes of Abu Simbel and Philae have thus been preserved in their entirety.

Six years later, in 1966, the sea inundated Venice, and a wall of water and mud from the Arno River flooded the churches, museums and libraries of Florence. International rescue efforts were quickly organized. Thousands of sculptures, paintings, manuscripts and books were rescued and restored.

By then it was clear that more than a quick and improvised response to such major crises was needed. In 1972, the ground-breaking Convention for the Protection of the World Cultural and Natural Heritage was adopted. It set a permanent legal, administrative and financial framework for international co-operation in this field. Nature and culture, often considered to be in opposition, were linked as complementary values in that innovative document. So far, some 100 countries have ratified the Convention, which is the world's most widely-agreed-to conservation pact. Not a lengthy travelogue

The first practical consequence of the Convention has been the compilation of the World Heritage List. Of its 315 current entries, 230 are cultural, 73 natural and 12 mixed". The Great Wall of China' America's Statue of Liberty, Italy's Venice and its lagoon, the Auschwitz concentration camp in Poland, the Kathmandu Valley in Nepal, the jesuit Missions of the Guarani Indians in Argentina, Brazil and Paraguay, Italian artist Da Vinci's painting of The Last Supper and Ghana's Ashanti traditional African buildings are all listed.

New sites are added every year. They must all have an exceptional, universal value and meet a set of rigorous criteria. Works of art in museums and certain endangered species do not qualify, for example. Cultural treasures must be authentic and influential, or in some way unique. A natural site must exemplify the state of geological or biological evolution on earth, or have exceptional beauty or large concentrations of animals.

Great care is taken so that the Heritage List does not become a lengthy travelogue. The decision to include an item is taken by specialists from 21 countries elected every two years from among Convention signatories.

Inclusion on the List automatically brings additional national and international prestige to the site, as well as a certain moral and political boost to local authorities or citizens trying to conserve the site, often competing for scarce funds.

It also means that the site will qualify for international aid from the World Heritage Fund, another offshoot of the Convention. About $2.7 million was disbursed in 1988. The Fund receives money from the Convention signatories and also accepts voluntary contributions from any other public or private source, including individuals.

Severely threatened sites have been placed on a special "List of World Heritage in Danger", which encourages urgent large-scale rescue operations and fund-raising. Seven sites are on the special list, including Haiti's historic Citadel and Sans Souci Palace and Zaire's splendid Garaamba National Park, the last refuge of the northern white rhino. Both have received considerable international aid.

The World Heritage List is not yet universal. A third of the countries of the world has not joined the Convention. But the World Decade for Cultural Development, with its emphasis on cultural identity, is expected to focus world attention on this crucial effort.