Water, combined with the nutrients of the earth, creates wood. With the proper application of friction and heat, wood, in turn, creates fire. When wood is reduced to ashes, it becomes a component of soil thus creating earth. The principle of mutual destruction holds that metal, in the form of tools, such as saws and axes, can destroy wood. The elements of water overcomes fire.
Wood can overcome earth by depleting the minerals and nutrients which make it fertile.
Fire consumes wood and earth traps water in depressions and dams. It is an internal system and is therefore most concerned with the cultivation of chi. When chi is held in the lower abdomen or tan tien, the body will be harmonious and stable. When chi erupts from the tan tien, power is produced to work the forge of the will. The power is held within until it is used and then regenerated.