"To follow the rule of acupuncture is to observe the sun, the moon, the stars, the four seasons and the eight correct seasonal energies. Acupuncture can be applied when the energy is stable......……

The eight correct energies are the guide to the observation of the deficiency and evil of the eight winds, and the arrival of the season."

(Ba Zheng Shen Ming Lun, Huangdi Neijing - Ch 26, The Yellow Emperor's Classic of Internal Medicine)