Tao Te Ching, or the Classic of the Way and Virtue, was written by Lao Zi about 2,500 years ago, around the time when Buddha was expounding the Dharma in India and Pythagoras was teaching in Greece.

"It is not only a precious gem in the treasure house of Chinese culture but a common spiritual wealth of the mankind," said China's senior official Jia Qinglin at a congratulatory message to the International Forum on Tao Te Ching, which started Sunday in Xi'an, capital of northwest China's Shaanxi Province.

The principle of being modest and peaceful in the book would provide an inspiring reference to China's ongoing construction of a harmonious society, said Jia, chairwoman of the National Committee of the Chinese People's Political Consultative Conference (CPPCC).

Tao Te Ching has influenced the Chinese people generation after generation, as well as people of different countries, races, nationalities and languages, he added.

"Today, in the 21st century, the ancient concepts and views of Tao Te Ching still have important values," said Liu Yandong, vice chairwoman of the CPPCC National Committee.

As one of the important classics of Chinese traditional culture, Tao Te Ching manifests a great profundity of thought contained in pithy remarks.

The book, consisting of only 5,000 characters, is a reflection of the lofty aspiration of the Chinese nation for amiability, happiness and harmony, said Liu.

The forum, jointly sponsored by Chinese Taoism Association and China Religious Culture Communication Association, will be held from April 22 to 27 in Xi'an and Hong Kong.

Involving 300 delegates from 17 countries and regions, it has been the first international forum of its kind that China has organized for the last 50 years.