All the books in the world.

The revival of the Library of Alexandria, one of the glories of the ancient world, could well be one of the high points marking the beginning of the twenty-first century. It also illustrates what the World Decade for Cultural Development is all about.

The new Library will be built on a striking site overlooking the Mediterranean Sea, where the Palace of the Ptolemy kings once stood. Egyptian President Hosni Mubarak and Federico Mayor, Director-General of UNESCO, laid the foundation stone in june 1988. The ambitious, 160-million project is being carried out by Egypt, with UNESCO's help. The first stage-a 200,000-volume library-will be completed by 1995. Eventually the library will house 8 million books.

Nothing remains of the original Library founded 2,288 years ago (about 300 B.C.) by Demetrios of Phaleron, a pupil of the Greek philosopher-scholar Aristotle. Therefore, the new library will not be a restoration, but a revival of the spirit and purpose of the original. It will focus on the history, geography and culture of Alexandria and the surrounding region-the Mediterranean basin and the Near East.

Tens of thousands of precious medieval manuscripts now deteriorating in Egyptian mosques, museums, monasteries and convents will be brought to the new library, where they will be restored and catalogued for the first time.

The library will be open to the public. Universities in the area will have direct electronic access to its computerized catalogue and data base. Information will relate to Greek and Middle Eastern antiquity, the meeting of Egyptian and Greek civilizations, the birth of Coptic Christianity and the influence of Islam, with special emphasis on the history of science in the ancient world. A regional information retrieval service will make it available to researchers all over the world.

An international school attached to the library will train its future staff and that of other institutions in the Middle East in advanced library science computer techniques.

The library is designed to host major international congresses. Its conference rooms-equipped with state-of-the-art communication facilities-will accommodate some 2,500 persons.

UNESCO has already contributed a feasibility study of the entire project and paid for a tour of major European libraries by two Egyptian officials. With the International Union of Architects, it will launch a $500,000 international architectural competition, funded by the United Nations Development Programme. It is also working to attract foreign donors for the project. The Egyptian Government so far has invested $60 million. Another $100 million still has to be raised. A tool of power

Famous for its lighthouse-one of the seven wonders of the world- Alexandria was for many centuries the centre of Hellenistic civilization. As part of the Roman Empire, it was second only to Rome. The Graeco-Roman civilization that flourished in Alexandria was to become one of the richest sources of classical Arab culture, particularly in science and philosophy.

What kept the Library going for 600 years was not philanthropy but a keen sense of realpolitik: the rulers of Alexandria used the Library as a vast intelligence gathering operation.

The astute Alexandrian sovereigns wanted to gain intimate knowledge of the peoples under their domination. They understood very well that information was a crucial tool of power.

For six centuries-between 3 B.C. and 3 A.D.-they brought together in Alexandria the greatest thinkers of the time-Euclid, the inventor of geometry; Erastothenes, who calculated the circumference of the earth; Herophilus, who established the rules of anatomy and physiology; Aristarchus and Dionysius Thrax, who codified grammar; and the founder of cartography, Claudius Ptolemateus.

Scholars were recruited from all corners of the vast Hellenistic world -from the Strait of Gibraltar to the banks of the Indus, from the Danube to Upper Egypt. They were lodged nearby in the royal palace, where they led the lives of recluses.

Those "living books" were on call to advise the rulers of Alexandria at any time of day or night. They also worked for the Library translating texts into Greek from their own languages.

Nearby, an army of scribes housed in the Library spent their lives copying manuscripts. Any written work brought by ship was systematically confiscated so it could be copied. At its height, the Library contained 30,000 works in 400,000 to 700,0046 papyrus scrolls.

How and why the Library disappeared remains a mystery. A fire probably ravaged it in 48 B.C. when the Roman Emperor julius Caesar, entrenched in the city, was attacked by the Egyptian fleet. Over the next five centuries, Alexandria was captured, recaptured and plundered by other Roman Emperors, Persian armies and, finally, the Arabs. The Library, as the rest of the city, must have been a victim.

But some historians believe that the Library just became obsolete, as codices, the ancestors of our modern books, replaced papyrus scrolls by the end of the third century A.D.

Whatever the causes of its destruction, the spirit of the Library of Alexandria, where three great civilizations met, will be revived before the end of the century.