Neidan is the Taoist practice of Inner Alchemy
. In Inner Alchemy practice, the human body becomes a laboratory, in which the energetic elixirs of refined Jing
(the "Three Treasures
") are cultivated and circulated. It is contrasted with Waidan - Outer or External Alchemy - in which herbal or mineral formulas are ingested by the practitioner. In Inner Alchemy, the body, mind and breath of the Taoist practitioner are used to bring about internal transformations.