The bamboo slips Fan yin (Anti-excessiveness) of the Western Han Dynasty, written in the form of conversation in 7-syllable prose-verse between hun (ethereal soul) and po (corporeal soul), with po as the host, and hun as the guest, reflecting the dualism of hun and po. In Huang di nei jing (Inner Canon of Yellow Emperor), appeared nearly at the same time, in which the hypothesis of all the five viscera embodies the spirit and its soul defined at the level of spirit-emotion, claiming that the physique and ethereal soul are born at the same time, and the spirit of Yang qi within the corporeal soul is the ethereal soul, which is different from the description in the Fan yin.