Below is the story of Zhong Yao recorded in Selected Essays on Chinese Calligraphy by Chen Si of Song dynasty.
When he was young, Zhong followed Liu Sheng to study calligraphy at Mount Niudu for three years. He also discussed brush techniques with Cao Cao (Emperor of the Wei State during the Three Kingdoms Period), Han Danchun, Wei Dan, Sun Zijing and Guan Pi. Once, he found the handwriting of Cai Yong (a famous calligrapher of the Han dynasty) on Brush Techniques in Wei Dan's possession. He begged Wei to let him borrow it but was refused. Zhong became so angry that he beat his chest and stamped his feet for three days, until he finally vomited blood. Cao Cao took out his panacea and saved Zhong from death. Later, after Wei Dan died, Zhong ordered people to open his grave and he finally got the essay of Cai Yong, from which he appreciated the meaning of the theory that ‘calligraphy with much strength and rich in sinew is of sage-like quality; that with neither strength nor sinew is sick. One must discover the secret and comprehend the essence of calligraphy, and it is best to apply the principles appropriately.’
On his death bed, he took out the essay from his pocket and said to his son, ‘I have been studying calligraphy for more than 30 years. I have learnt so many methods without success, until I learned Cai’s brush techniques. Whenever I meet a friend, we will discuss calligraphy by writing on the ground. My bedclothes were lacerated due to my practice on them with my hand. I would stay in the toilet the whole day thinking of calligraphy, and forget that I am in the toilet. I also imitated the living things in nature from the calligraphic point of view.’