Jing (Chinese: ?; Wade-Giles: ching1) is the Chinese word for "essence", specifically kidney essence. Along with qi and shen, it is considered one of the Three Treasures Sanbao of Traditional Chinese Medicine or TCM. According to tradition, Jing is stored in the kidneys and is the most dense physical matter within the body (as opposed to shen which is the most volatile). It is said to be the material basis for the physical body and is yin in nature, which means it nourishes, fuels, and cools the body. As such it is an important concept in the internal martial arts. Jing is also believed by some to be the carrier of our heritage (similar to DNA). Production of semen, in the man, and menstrual blood (or pregnancy), in the woman, are believed to place the biggest strains on jing. Because of this, some even equate jing with semen, but this is inaccurate; the jing circulates through the eight extraordinary vessels and creates marrow and semen, among other functions.[1] One is said to be born with a fixed amount of jing (pre-natal jing, also sometimes called yuan qi) and also can acquire jing from food and various forms of stimulation (exercise, study, meditation.) Theoretically, jing is consumed continuously in life; by everyday st ess, illness, substance abuse, sexual intemperance, etc. Pre-natal jing by definition cannot be renewed, and it is said it is completely consumed upon dying. So, this jing is considered quite important for longevity in TCM. Many disciplines related to qigong are devoted to the replenishment of "lost" jing by restoration of the post-natal jing. In particular, the internal martial arts (esp. T'ai chi ch'uan) and the Circle Walking of Baguazhang may be used to preserve pre-natal jing and build post-natal jing - if performed correctly. Commonplace in China is the sight of Ginseng on sale in herb shops, at a wide range of prices - Kung Fu classics fans may remember it used as a plot element at the start of Drunken Master 2. Ginseng, particularly Korean and Chinese, is said to bolster the jing. An early mention of the term in this sense is in a 4th century BCE chapter called "Inner Training" () of a larger text compiled during the Han dynasty, the Guanzi ().[2] Jing (?; essence) should not be confused with the related concept of jin (?; power), nor with jing (?; classic/warp), which appears in many early Chinese book titles, such as the Nei Jing, yi jing and Cha Jing, the fundamental text on all the knowledge associated with tea.