In Chinese Taoism thought, things in nature can be classified in five types: metal, wood, earth, water, fire (金 木 土 水 火) . These five elementss (五行) are not just the materials that the names refer to, but rather metaphors and symbols for describing how things interact and relate to each other. The original Taoist reference was about the seasons (or the heavens), and they would then be more accurately described as the five phases. In Taoism, everything we know or think of as reality is a symbol, and a reflection of the heavens, so by understanding the macrocosmic relationship of things we can understand these same relationship on a smaller scale: in the body, in personal astrology, or in politics.
Taoism describes both a production (生 Sheng) cycle and a control (克 Ke) cycle acting upon the elements. In the production cycle, wood produces fire; fire produces earth; earth produces metal; metal produces water; water produces wood. In the control cycle, wood controls earth; earth controls water; water controls fire; fire controls metal; metal controls wood. The production cycle outlines a pentagon and the control chain outlines a five pointed star. These interactions and relationships form a framework for different schools of philosophy. The interaction of five elements becomes a tool that helps taoist scholars sort out observations and empirical data. Based on observations of how things interact, things are classified into one of the five elements so that they fit into the observed pattern. Then one can draw high level conclusions or predictions based on the element types.
In Chinese medicine, each organ of the human body is associated with an element. The liver, tendon, eyes are of the wood element type; heart, blood vessels, tongue are fire element type; spleen, muscle, mouth are earth element type; lungs, skin, hair, nose are metal element type; kidney, bone, ears are water element type; etc. This classification is followed in diagnosing and adjusting the balance in the body. To further understand this, in Chinese medicine, the organs are not simply anatomical organs we understand in western medicine, but actually refer to phases, system, and energies in the bodies. These include the above mentioned body parts, as well emotions linked to each phase, a sound of voice, a smell, a direction, a food, a taste, etc.
In herbal medicine the properties and effects of each herb are classified according to empirical observations on how the herb affects the body. For example, if one herb causes dry mouth and chapped skin, it would be classified as "fire" type. The element type of the herbs can serve a useful purpose when designing a herbal cocktail remedy because the "fire" ingredient can be controlled by adding some "water" ingredients; or the addition of "metal" ingredients can assist the "water" ingredients to do their job in controlling the "fire". A "water" type herb or food is believed to benefit a "wood" type organ etc. The principle of the five elements is used extensively in Chinese medicine.
While these five elements or phases are used by all branches of Chinese medicine, there is also a branch of Chinese medicine that calls itself The Five Element School. This branch tends to focus on the psycho-emotional component of health and it treats solely on a constitutional basis, and only uses acupuncture and moxa. The Five-Element School was founded by J.R. Worsley who founded the Worsley Institute of Classical Acupuncture in England and in the US. The practice is still largely an oral tradition in the states, passed down from master to a student already holding an acupuncture degree. However their protocols are becoming mainstream enough among practioners that they are being included on national board exams.
The study of Feng Shui focuses on how the five elements within people, objects and the landscape, affect the harmony of the environment. Even Chinese astrology is based on the five elements. The five visible astrological planets are associated with the five elements: Venus is metal; Jupiter is wood; Mercury is water; Mars is fire; Saturn is earth.
It appears that there may have been cultural transmission between Egypt and China at a very early time, because the sequence given immediately above, which first occurs in the Bo Hu Tong, is the reverse of the sequence of the five visible planets used to name the five days of the week exclusive of Sunday and Monday. The Western sequence is Saturn, Mars, Mercury, Jupiter, and Venus, whereas the Chinese sequence is Venus Jupiter, Mercury, Mars, and Saturn. The arrangment in nature (whether one examines distance from the sun or how fast the planets move across the nightime sky from day to day) is Mercury, Venus, (Earth), Mars, Jupiter, Saturn. It is well known how the Egyptian sequence was obtained, the sequence that eventually passed into Western calendars. Information regarding the formative process in China appears to have been lost, but applying a simple variant of the Egyptian rule provides the Chinese sequence. See the details at this site.
Western parallels and contrasts, revolving instead around only four elements, called the "temperaments" or the four humours in Western physiology, psychology and pre-scientific medicine, from the time of the pre-Classical Greeks until the 18th Century Enlightenment, also informed the historical study called alchemy that led to chemistry.\n