While some shall remain lost forever, others are fortunate enough to come into daylight again, offering priceless clues to the past.

A secret celadon and glazed ware are just two of the latter that have been recovered.

Secret celadon

In many ancient literary works, the word "mi se ci" (secret celadon) never fails to inspire people's imagination.

Its earliest mention was in a poem, "Mi Se Yue Qi (Secret Celadon in Yueyao Kilns)" by Lu Guimeng, a poetic scholar of the Tang Dynasty (AD 618-907).

"In the wind and dews of the deepest autumn, the Yueyao kilns opened again, with the secret celadon capturing the lively green colour from 1,000 mountains," the poem so describes.

Another romantic poet, Xu Yin of the Five Dynasties (AD 907-960), described the method behind the creation of the secret celadon as to: "Take a part of the bright moon and dye it with spring water, whirl the thin ice to contain the green cloud."

These and other descriptions did little to clarify the making or the nature of the secret celadon, only arousing people's curiosity ever more.

All scholars knew about the piece was that such high-quality porcelain was made solely for emperors in the imperial Yueyao kilns located in today's Zhejiang Province of East China.

In 1987, when the local government of Fufeng County in Northwest China's Shaanxi Province decided to refurbish the Famen Temple, little did they expect to find a number of treasures in an underground chamber officially sealed in AD 847.

In the ups and downs of history, the story of the sealed palace had been lost.

Among the findings were 13 porcelain works in the shape of bowls, plates and trays. Archaeologists and ceramic experts were thrilled to find in a record of the underground palace that the art works were the "mi se ci" granted by the Tang emperors to the temple.

In 1995, the Museum of Famen Temple held a seminar on the secret celadon in Shanghai, which attracted over 100 scholars from home and abroad.

The scholars agreed the name of the porcelain referred to its rare glaze that ranged from light green to a bluish tone, rather than the secret production method that had been lost centuries ago.

The 13 porcelain works found at the Famen Temple all bear a lovely green tone like a spring lake.

Ceramic experts said such rare colour comes from reaching a certain temperature just before the end of firing in a kiln.

In the early Tang Dynasty, most kilns still fired clay works by piling them up, which often resulted in uneven surfaces and glaze colours.

But in Yueyao kilns, skilful potters had invented convenient containers for each single clay work. The containers were also piled up, but in such a way that all works could gain the most suitable firing condition.

In the following dynasties, the techniques were continued and eventually reached new peaks in the Song, Ming and Qing dynasties.

The discovery of the secret celadon works at Famen Temple has great importance.

Since the 1950s, archaeologists have found a number of ceramic remnants or works that had the rare green glaze. But it was not until the Famen Temple celadon was discovered that scholars were finally able to categorize the works.

An uncovered plate with a diameter of 24 centimetres has the 7-centimetre tall rim formed like five large petals of a sunflower. In sunlight, the plate looks like it is holding water - it is a good footnote to the description of the "bright moon" and "spring water" made by Xu.

Another bottle weighing 615 grams stands at 22 centimetres. Its long elegant neck and full round body are made more mellow with eight vertical ridges.

On its jade-like body is a light trace of the painting that was used to wrap the bottle.

Among the 13 works, there are two bowls that have silver and gold inlaid rims.

They are so special because the flower and bird patterns on them were painted with lacquer, a technique that originated from lacquerware.

The bowls give clues to the earliest stages of applying gold and silver on to ceramics.

Glazed ware

Archaeological findings have proved that as early as the Western Zhou Dynasty (1146 BC - 771 BC), Chinese people had mastered the technique to make glazed ware, which had already appeared in the Middle East in the 16th or 15th century BC.

But unlike ceramics, glazed ware in China was confined to simple beads or small decorative objects for a long time.

In the Tang Dynasty, cultural exchanges brought glazed ware into China that were seen as more valuable than gold.

Among the treasures of Famen Temple were 20 glazed items, 18 of which came from the Islamic world.

The intact works carry techniques like colourful glazing and cut patterns in distinctive Islamic styles.

A light yellow plate with pomegranate patterns was the only colourful glazed ware found in the temple. It was also the earliest colourful glazed ware found so far in the world.

With a diameter of 14.1 centimetres, the plate weighs 84 grams and its rim is 2.7 centimetres high.

On the background painted in gold are two pomegranate flowers and a fruit.

They form a simple, but interesting picture with two decorative circles and 12 crescents on the rim.

Another 21.3-centimetre tall yellowish bottle looks interesting with four layers of decorative patterns.

Below the first layer of dark purple dots lay some yellow patterns that look like a fish shape. Near the bottom are some larger yellow dots lined between dark purple rain drop patterns.

Inside the bottle is a note written in ink. Among the dozen words only two - "zhen lian" or "true lotus" - can be made out.

The bottle appears quite similar to another bottle treasured in the Metropolitan Museum of Art in New York. Both were made around the early 9th century on the eastern coast of the Mediterranean Sea.

Although much simpler than the imported works, they are fine examples of how Tang Dynasty craftsmen learned eagerly from more advanced counterparts, as well as the benefits of an open-minded cultural policy at the time.

The Chinese version of this article first appeared in the second issue of this year's Collections magazine.

(China Daily February 13, 2003)