Eight Principles of Yong
The "Eight Principles of Yong" are the principles of Chinese calligraphy. Yong (Simplified Chinese: 永) is a Chinese character that contains all the common strokes: drop, horizontal stroke, vertical stroke, hook, rising stroke, left-falling stroke and right-falling stroke. Many calligraphy experts practice this character a lot to promote their skills.
There was a famous calligrapher called Wang Xizhi in ancient China. He once went to a mountain and was absorbed by the beautiful view and so decided to stay there. One day when he fell asleep at the top of the mountain he had a vivid dream. In the dream he met an old man who wrote a character on his hand. He told Wang Xizhi to practice writing this character many times until it is perfect and by doing this his calligraphy skills would improve greatly. When he woke up, he gazed at his hand and the character was there. He took the old man's advice and practiced it a lot. In the end he became one of the most famous calligraphers in China and created many great works. He also passed on this principle to later generations.
There are many versions of explanations of "the Eight Principles" and the most famous one was written by Chu Zongyuan. The drop should lean to another side "suddenly", like a bird. Writing the horizontal stroke should apparently resemble part of a horse. The vertical stroke is like a jade, meaning that you have to use your strength. The hook is just like a person jumping. Writing the rising stroke is like spurring a horse. The left-falling stroke is like a horse grazing and the short one is like a bird pecking off. Finally, the right-falling stroke is like parting the body.
Although it is called the principles of Yong, it can be regarded as the principles of Chinese calligraphy as it contains all the kinds of strokes found in Chinese characters.