Illustration from an edition of 1599 (27th year of the Wanli reign period of the Ming dynasty) -- table of the correspondences between the zang and fu viscera, the eight trigrams and the 12 divisions of the day. Shangjiao (the Upper Burner), zhongjiao (the Middle Burner), xiajiao (the Lower Burner), the liver, the heart, the spleen, the lungs and the left kidney correspond respectively to the qian (Heaven), gen (Mountain), xun (Mild Wind), zhen (Thunder), li (Fire), kun (Earth), dui (Lake), and kan (Water) trigrams. The twelve divisions of the day, i.e.
Zi (11:00 pm - 1:00 am), Chou (1:00 - 3:00 am), Yin (3:00 - 5:00 am), Mao (5:00 - 7:00 am), Chen (7:00 - 9:00 am), Si (9:00 - 11:00 am), Wu (11:00 am - 1:00 pm), Wei (1:00 - 3:00 pm), Shen (3:00 - 5:00 pm), You (5:00 - 7:00 pm), Xu (7:00 - 9:00 pm) and Hai (9:00 - 11:00 pm) correspond to the gall bladder, liver, lungs, large intestine, stomach, spleen, heart, small intestine, bladder, kidney, baoluo (Heart Envelope) and sanjiao (Triple Burner). Knowledge of this system of correspondences is considered helpful in understanding temporal patterns of change in the physiological functions and pathologies of the internal organs.
