About the 5 elements ?
On the north half of earth, the South is warmer than the North, so ancient Chinese people believe the fire elements is on the South, the ice(water) elements is on the North. The sun is come out from East and go down at West, the trees(wood) need face the sun to get warmer and growing strong, so people believe the wood element is from East, because metal is heavy and cooler than wood, so when the sunset, the temperature is cooler of the day, Sun is heavy down at west side, so people believe the metal elements is on the west side. The earth is under every where, so people believe the earth is in the center. So that is why in one year, people believe wood is spring, fire is summer, metal is fall, ice(water) is winter, and the earth is long summer combine in 4 seasons.
In human being's internal organs, people believe Heart is fire elements, becase it control blood move in the body, ancient people believe blood is fire+water, so it is red color. The heart must keep warm to move the blood. The kidney is water elements, bease it control the body liquid movement and build up urination to send out of body's useless liquid. The liver is wood elements, it connect the heart and kidney's energy, like tree connect the sky and earth. If heart give warm energy to liver and kidney give water energy to liver, so the liver(wood) will work well. And the lung is metal, it is heavy and need cool down, so it can breath smoothly and inhale oxegyn and exhale useless Qi. The spleen is the earth element it suppor energy to all the other four organs specialy for Lung(metal), because metal is come out of earth, so people believe metal is essent of
In our nature world, wood can be fired, that mean wood born fire, and after fire, every thing become dust, that is earth, so fire born earth, inside the earth, there is metal, so earth born metal, metal come out of earth will rust, become liquid, so metal born water, the water can moist the root of a tree and make tree grow up. So water born wood. this is the circle of 5 elements.
In the other way, tree's root eat earth to get nutrition, so wood kill earth, earth can stop water. So earth kill water, the water can cover the fire, so water kill fire, the fire can melt the metal, so fire kill metal, metal knife can cut wood, to metal kill wood.
So Liver kill Spleen, people got sick of digest problem, Spleen kill Kidney, people get water swollen, the Kidney kill Heart, people get blood circle problem, the Heart kill Lung, people easy get breath problem, Lung kill Liver, the people easy angry or got emotion problem.
To build a harmony health body, we need more balance on internal organs, that is liver born heart, heart born spleen, spleen born lung, lung born kindey, kidney born liver.