Why is China's calligraphy called a treasure?

China's calligraphy has been passed down for thousands of years and is unique in the world. There are many precious calligraphy handed down, which can be said to be priceless. Many people all over the world want to learn from China's calligraphy. The United Nations has listed China's calligraphy as a world cultural heritage. Therefore, China's calligraphy is a national treasure and a wonderful work of the world!