Originally a moral theory associated with Zisi, the grandson of Confucius, and Mencius. In the 3rd century BC, the sage-alchemist Zou Yan introduced a systematic cosmological theory under the same rubric that was to dominate the intellectual world of the Han dynasty (206 BC–220 AD).
In ancient Chinese cosmology, the five basic phases or 'elements' that explain change in the cosmos are earth, wood, metal, fire, and water. These elements were believed to overcome and succeed one another in an immutable cycle and were correlated with the five cardinal directions, seasons, colours, flavours, plaets, tones, etc.
In English the word "element" has a different connotation why the Chinese prefer calling the theory the Five Transformations or the Five Phases.
The Five Elements are believed to be the five basic elements of the universe in which they produce and overcome - create and destroy - each other in a never ending cycle. It is the smooth and harmonious transition from one phase to another that is important, along with the balance between them.
The theory views the Universe and its function as being cyclical and interactive. Accordingly, all of the things in universe are interdependent. Everything in existence contains some quantity of all five elements; however, according to the theory one of the five predominates in each thing and may thus be categorized accordingly.
Taoist physicians and sages determined that each element had a special relation with particular organs in the human body as well as to other things such as colors, flavors, the time of day, the season of the year, and the way we respond physically and emotionally to external influences and all of the forces of nature. In this way the Five Elements is fundamental to Chinese Medicine and lack of health is seen as caused by an imbalance.
The Five Elements theory identifies the five different modes (elements) in which chi energy may manifest itself. The five (Wood, Fire, Earth, Metal and Water) are arranged into a cyclical sequence that represents the flow of energy between these elements as 'phases'.
Each phase of an element characterizes a stage in a cyclical process. The characteristic of each phase is determined by the 'energy dynamic' personified as the never ending round of the seasons in the natural world.
It is not to say the passage of time that changes things; everything changes anyway. Thus the 5 elements theory is simply an observation on natural changes; everything can be in constant and harmonious transition from one phase to another - just as one season 'becomes' the next.
Wood is the most human of the elements. It is the element of spring; the urge to achieve and the force of growth and flexibility. This element represents all the activities of the body that are self regulating and function without conscious thought; i.e. digestion, respiration, heart beat and basic metabolism.
Fire is the element of heat, summer and enthusiasm; nature at its peak of growth, and warmth in human relationships. Its motion is upward and is the symbolic of maximum activity indicating that decline is then inevitable.
Earth is the element of harvest time, abundance, nourishment, fertility, and the mother to child relationship. This element is also regarded as central to balance and the place where energy becomes downward in movement. It is the symbol of stability and being properly anchored.
The force of gravity, the minerals within the earth, the patterns of the heavenly bodies and the powers of electrical conductivity and magnetism. Metal has structure, but it can also accept a new form when molten. Metal energy is consolidating and with inward movement, like a flower closing its petals. The symbol of metal is one of a cutting and reforming action, but it is also regarded as a solidifying process.