There are five organ networks: Metal, Water, Wood, Fire, and Earth. Each is associated with its own meridian and set of functions.
Fire network (火行): the heart meridian (心経)
The heart is considered the ruler because, like a benevolent and enlightened monarch, it is all-knowing and ever-present, sharing its wisdom unconditionally for the good of the whole. Our fire aspect represents fulfillment: the total expression and integration of our being, the full extent of our expansion, maturation, and development.