Source: Treatise Of Cosmic Fire
From the very use of the term "sheath" it will be noted that we are considering those fires which manifest through the medium of those externalities, of those veils of substance which hide and conceal the inner Reality. We shall not here take up the subject of the sheaths on the higher planes, but simply deal with the fires that animate the three lower vehicles - the physical body in its two divisions (etheric and dense), the emotional or astral body, and the mental sheath. It is frequently overlooked by the casual student that both the astral and the mental bodies are material, and just as material in their own way, as is the dense physical body, and also that the substance of which they are composed is animated by a triple fire, as is the physical.
In the physical body we have the fires of the lower nature (the animal plane) centralized at the base of the spine. They are situated at a spot which stands in relation to the physical body as the physical sun to the solar system. This central point of heat radiates in all directions, using the spinal column as its main artery, but working in close connection with certain central ganglia, wherever located, and having a special association with the spleen.
