Cai Yong, courtesy name Bojie, came from Yu in Chenliu (south of modern Qi County, Henan); he loved letters, numerology and astronomy and played music well. Summoned to office in 170, he collated texts in the Eastern Pavilion library and became a court counsellor. In 175 he and Tangxi Dian asked to fix an authoritative text of the classics; with Emperor Ling's approval Cai wrote the characters on the stelae himself, and they were set up outside the Imperial Academy as the Xiping Stone Classics. A sealed memorial of 178 angered the eunuchs and he was exiled to Shuofang; amnestied but afraid to go home, he spent twelve years in hiding in the Wu and Kuaiji region. Dong Zhuo later forced him back to court with high rank. When Dong was killed in 192, Cai sighed over him in Wang Yun's presence and died in prison at sixty-one. His biography tells how he made the Scorched-Tail Zither from burning paulownia; his daughter Cai Yan was also a writer.
Cai Yong, courtesy name Bojie, was a man of Yu in Chenliu. Moved by earlier writers who framed an objection in order to answer it, he wrote the Shihui. At the Dongguan archive he had joined Lu Zhi and Han Yue in compiling a supplement to the Later Han records, and he later submitted a memorial presenting the Ten Treatises he had written.