The etheric body, in the vast majority of humans, is the vehicle or the instrument of astral energy. It gives vitality, health, life and organization to the physical body. It steps energies from the higher bodies down into our physical consciousness. The etheric body is composed of interlocking and circulating lines of force emanating from the many levels of consciousness of our planetary life. These lines of energy and this closely interlocking system of streams of force are related to the seven energy centers (chakras) found within the etheric body. Each of these centers are related to certain types of incoming energy. When the energy reaching the etheric body is not related to a particular center, that center remains passive; when it is related and the center is sensitive to its impact, then that center becomes vibrant and receptive and develops as a controlling factor in the life of the man on the physical plane. The dense physical body is held together by and is expressive of the energies which compose the etheric body. As attitude, attainment and comprehension shift to higher levels, the etheric body will be constantly changing and responding to newer energies. The etheric body interpenetrates, underlies, and occupies the entire physical organism. It extends beyond the physical form and surrounds it like an aura. According to the point in evolution will be the area which the etheric body covers beyond the outside of the physical body. It may extend for a few or many inches. Within the physical body, the network of the etheric body is to be found permeating every single part. It is particularly associated at this time with the nervous system, which is fed, nourished, controlled and galvanized by its etheric counterpart. This counterpart is present in millions of tiny streams or lines of energy, to which the Eastern occultist has given the name nadis. There are 72 000 nadis, which act as carriers of energy. They are in fact the energy itself and carry the quality of energy from some area of consciousness in which the soul in the body may happen to be focused. According to the state of consciousness and the psychic state of awareness, so will be the type of energy carried by the nadis, passing from them to the outer nervous system.