On the base of deficient right-Qi, the pathogenic wind, cold, wet, heat attack the human body, block muscle, channel and joints and cause stagnant movement of Qi and blood.

It is believed that this disease results from kidney deficiency in the root, and wind, cold, dampness and blood stasis in the tip;

Not only the evils of wind, cold, dampness and heat, but also depression of gan-qi can result in bi-zheng.