The element of your lunar sign will exercise their influence on your life. A fundamental part of Oriental philosophy is the interrelationships among the five elements. In this context, the metal could mean a vessel or container for holding water, so we can say that metal traps water. In another sense, metal is the only element that will change into a liquid when heated. From Water we get Wood.
Water here means the rain or dew that makes plant life flourish, thus producing wood in the process.
From Wood we get Fire. Fire cannot exist by itself but is produced by burning wood. From Fire we get Earth. Symbolically fire reduces everything into ashes, which becomes part of the earth again. From Earth we get Metal.