One of China's literary treasures is now on show until mid-September in the ancient books exhibition room at the far end of the second floor of the National Library of China's main building.

The library is hosting a rare display of the 600-year-old Yongle Encyclopedia, featuring nine samples on sandalwood pedestals in glass cases.

Despite their age and rocky history, the books, recently restored by the library, are still as elegant as ever. The encyclopedia originated in 1403, when Zhu Di (1360-1424) of the Ming Dynasty (1368-1644) ordered that a giant set of reference books be compiled to show off his literary exploits.

The volumes carried the same name that Zhu Di chose for his reign -- Yongle (everlasting happiness). It took more than 3,000 people four years to complete the project.

Its 22,877 titles were divided into 11,095 volumes, making it the largest encyclopedia in the world at that time.

The series includes content from more than 7,000 earlier books, more than any other in China's history. Thanks to the project, many books and writings that would otherwise have been lost to history were saved.

When Emperor Qianlong of the Qing Dynasty (1644-1911) decided he also wanted to leave a great cultural legacy during his rule (1736-95), the Siku Quanshu (Complete Library of the Four Branches) was compiled under his decree. It included the content of about 500 books extracted from the Yongle Encyclopedia.

But the encyclopedia has been threatened with destruction ever since it was first created. Because of its huge bulk, Zhu Di never made up his mind whether to publish it widely and, apart from the original manuscript, only had one other copy transcribed.

In 1557, the only copy of the encyclopedia narrowly escaped being burnt in a fire which demolished three palaces in the Forbidden City. The then emperor Jiajing decided to have another copy of the encyclopedia made.

The making of the copy was itself a memorable project. It took some 100 scribes, selected via strict exams, six years to complete the task, with each contributing three pages a day.

Their names, as well as those of the proofreaders, were signed at the end of their particular volumes so that any mistake could be traced and those responsible for it punished.

Remnants of this second copy are all that we have today.

The original manuscript was totally destroyed in a fire in the middle of the Ming Dynasty, while historians are unsure what happened to the first copy.

Not much is left of the second copy. During the Qing's long reign, much of it was damaged by negligence and theft.

During the two Opium Wars in the 1840s and in 1900, the invading Western powers burnt and took away most of the volumes.

According to China Encyclopedia, part of up to 800 volumes of the Yongle Encyclopedia are still stored on the Chinese mainland.

The National Library of China has 161 of them.

(China Daily August 11, 2003)