Duan Yucai

He made great contributions to the study of Historical Chinese phonology, and is known for his annotated edition of Shuowen Jiezi.

A native of Jintan, Jiangsu, he resigned his government post at the age of 46 to concentrate on his studies.

A student of Dai Zhen, he divided Old Chinese words into 17 rhyme groups.

He suggested that "characters sharing the same phonetic component must belong to the same rhyme group [as deduced from the rhyming scheme of Shijing]" (同聲必同部).

His monumental Shuowen Jiezi Zhu (說文解字注 "Annotated Shuowen Jiezi"), which he spent 30 years to complete, was published shortly before his death (in 1815).