In Chinese medicine [Jing] is the essence of organic life. It refers to the material substance, physical structure and sensate life of a person - the tangible aspects. [Jing] has two sources: that which a person is born with and that which is created whilst living. The quantity and quality of prenatal [Jing] ( [xian-tian-zhi-Jing]) is fixed at conception. Together with original [Qi], prenatal [Jing] determines as person's basic makeup and constitution. Postnatal [Jing] ( [hou-tian-zhi-Jing]) is derived from ingested food. Disharmonies of [Jing] manifest during development, maturation and reproduction.