The Five Elements
The basic theory behind the 5 Elements is there are “different kinds” of qi in nature. In Chinese Traditional Medicine, or Oriental Medicine, they are represented as water, wood, fire, earth, and metal. These five represent a class of qi which takes many forms.
One way they interact is that one will feed to the next one. It is called Inter-promoting. Water is the essential for life as we know it, so the Five Elements starts there. It allows for wood to grow, and wood is the fuel for fire to burn, the ashes of burned wood turns to earth, metal is found in earth, and water condenses on metal. Then, the cycle is back at water. This is why it is called inter-promoting. It is also known as a parent/child relationship. Water is the parent of wood, so the qi of water is passed down to give nutrients to wood. Wood promotes fire, fire promotes earth, earth promotes metal, and metal promotes water. In inter-promoting, yin always promotes yin and yang always promotes yang.
There also is the connection between the elements that keep others in check. The diagram's star in the middle of the circleis called Inter-restraining. The theory works by when the water qi gets too strong, fire has to bring it back in line so the rest of the elements are balanced. Now, extend this basic flow to all the elements: water restrains fire, wood restrains earth, fire restrains metal, earth restrains water, and metal restrains wood. And the way to remember it is water puts out fire, trees (wood) keeps the ground/dirt (earth) from being blown in the wind or washed away in a flood, fire melts metal to be shaped, earth is used to create dams, and metal axes cut down the trees.
There is a story about how a village was wiped out because they didn't follow the cycle of nature.
They had an old belief that if they did not respect the neighboring mountain's forest, the mountain god will take its revenge on the town. Later, when people started to forget the 'old superstition', they took out the forest to sell as lumber. Later that year they had heavy rain in the area. Because there were no trees to hold back the dirt (earth) on the mountain, the water and mud slid down the mountain and wiped out the village.
In the Five Elements, water promotes wood and wood restrains earth. Since there was no wood to absorb the water and fire was weaked from the excess water, the water energy rushed to the next absorbing element of earth. The lack of wood to restrain earth was gone so there was a massive mudslide.
A balance in the Five Elements will affect us if we know of it or not.
Each category of Water, Wood, Fire, Earth, and Metal represent many energies from organs to planets. Knowing this chart will greatly improve one's Wu Gong practice.