In neidan, the human body becomes a cauldron (or "ding") in which the Three Treasures of Jing ("Essence"), Qi ("Breath") and Shen ("Spirit") are cultivated for the purpose of improving physical, emotional and mental health, and ultimately returning to the primordial unity of the Tao, i.e., attaining Taoist Immortality. It is believed the Xiuzhen Tu is such a cultivation map. In China, it is an important form of practice for most schools of Taoism.