Jianchu Twelve Spirits
The twelve terms—Jian, Chu, Man, Ping, Ding, Zhi, Po, Wei, Cheng, Shou, Kai, Bi—rotate daily, changing monthly with the 'Jie' (solar term), and their boundary aligns with the month pillar in Bazi. It is one of the primary bases for determining auspicious and inauspicious days in the Chinese almanac.
The Jianchu Twelve Spirits is one of the primary systems used in the traditional Chinese almanac to determine daily auspiciousness and inauspiciousness. It comprises twelve terms—Jian, Chu, Man, Ping, Ding, Zhi, Po, Wei, Cheng, Shou, Kai, Bi—which take turns governing each day. The monthly changeover is based on solar terms, aligning with the month pillar division in Bazi. Historically, when selecting dates for activities, people would consult the name of the reigning spirit to judge suitability, such as 'Jian day' being favorable for starting a business, while 'Po day' is often avoided. This forms the foundational basis for the auspicious/inauspicious listings in the almanac.