The 5 elements form 2 cycles. A promoting cycle where one element gives birth to the next. A retraining cycle where one element restrains another. The balance of both cycles, under normal circumstances, ensure the harmony and nature of the body and the world.
生生不息- The Never Ending Circle of Life (The Sheng Cycle)
The promoting cycle is one where one element promotes, nurtures or generates the next element. This is one of a mother- child cycle, where one gives birth to the next.
木生火- Wood gives birth to fire. This goes without saying… Human discovered fire when woods were rubbed together. When we go camping, we know that we need wood to build fire.
火生土- Fire nourishes the earth. As fire dies down and leaves behind ashes, it nourishes the earth and makes the soil rich. From ancient farming practices, forests were burned down to give way for rich soil that would give plenty of harvest.
土生金- Metal in its elemental form is made up of different minerals, which is found in the soil. When we want to find metal such as iron, gold, copper, etc, we have to mine them from the earth. Therefore Earth gives birth to metal.
金生水- Metal gives birth to water. This is a bit of a hard one. At first I thought that perhaps due to is cooling nature, vapour would condense on the surface of metal and thus the ancients observing this came up with the theory that metal gives birth to water. However, another explanation is that metal tools are used to discover and hold water.
水生木- Water gives birth to wood. This one is easy. Without water we all know that plants cannot grow very well.
相剋- The Inter- Restraining Cycle (The Ke Cycle)
Each element also has a restraining effect on another. This restraining relationship skips a generation, and is considered a grandparent- grandchild relationship.
木剋土- Wood inhibits earth. I looked up a few explanation for this. Some says that it’s because wood draws up nutrients from earth, thus making the earth weaker. Some say it’s because wood is used to mold the earth into a dam. While I can kind of understand the analogies of both, I thought of one that makes more sense to me. If we look from the perspective of soil erosion, we can see how earth will quickly get flushed away by harsh weather in a deforested area. I believe that wood restrains earth as the root system of a forest keeps the soil in their place.
土剋水- Earth inhibits water. The boundary between land and water all over the world, is vast area of beach. During flood, earth is used to build dam to prevent water from flowing inland.
水剋火- Water inhibits fire. I am pretty sure this doesn’t need much explanation lol…
火剋金- Fire inhibits metal. I think the word “inhibit” is probably not the best choice but I suppose it’s difficult to properly translate. What it means is that fire can melt metal, causing it to change from its solid state to liquid state. This relationship comes in handy when human beings use this property to make tools.
金剋木- Metal inhibits wood. The metal tools that are molded with fire are then used to cut down trees. Also, when the earth is too rich in metal (like ones with too much iron, too much copper, gold, etc), it actually makes it difficult for plants to grow.
These 2 cycles keep each other in balance. Because each element is promoted by one and controlled by another, this 2 cycles ensure no one element becomes too excessive or deficient.
Take the relationship between wood, fire, and water for example. Fire draws its strength from wood, but at the same time it is restrained by water. Water promotes growth of wood which will again promote the growth of fire. It’s almost like a feedback loop within the 3 elements. Of course, it gets more complicated when all 5 elements are considered and Yin Yang theory is layered over it. This is just a very basic example.