Accounting for the differences between Zhen(真) and Wen(文) rhymes on one hand, and Zhi (脂) and Wei (微) on the other, is a
challenge to the researcher.
Jiang Yong (江永) did not succeed in his attempt to make a clear taxonomy and his failure can be attributed to his overlooking the relationship between Xian (先) and other types of rhymes. Another aspect JIANG Yong (江永) failed to take into consideration deals with the difference in the main vowel between Zhen (真) and Wen (文). Similarly, like JIANG Yong, DAI Zhen (戴震) did not separate Zhen (真) and Wen (文) rhymes, for the same reason. Moreover, he singled out a new category, Ji (祭).
Duan Yucai (段玉裁) started his own rhyme taxonomy on the basis of ancient documents and pointed out that Zhen (真) and Wen (文) were separated in the period prior to Shi Jing's(诗经 Classics of Poems) time and that his method consisted of 3 parts: first, he took up the sound component of characters; second, he analyzed the close syllables of Chinese and third, he used the taxonomy of rhymes of Shi Jing (诗经). The research reported here makes use of the Guodian (郭店) bamboo slips' version of Lao Zi (老子) together with The Comments of Confucius on the Poetry from Shanghai Museum's collection of bamboo slips in order to prove DUAN Yucai's (段玉裁) point. It is found that the latter work particularly is interesting, for it could be discovered that the slips numbered 21 and 22 both contain a toponym, 宛丘 which was written as甸丘, thus leading to the conclusion that Zhen (真) and Wen (文) rhymes were already partially undistinguishable by the time of the Warring States.