d "etheric" because it is built--of
that finer kind of matter by the vibrations of which light is conveyed to
the retina of the eye. (This must not be confused with the true aether of
space--that of which matter is the negation.) This invisible part of the
physical body is of great importance to us, since it is the vehicle through
which flow the streams of vitality which keep the body alive, and without
it, as a bridge to convey undulations of thought and feeling from the
astral to the visible denser physical matter, the ego could make no use of
the cells of his brain.

The life of a physical body is one of perpetual change and in order that it
shall live, it needs constantly to be supplied from three distinct sources.
It must have food for its digestion, air for its breathing, and vitality
for its absorption. This vitality is essentially a force, but when clothed
in matter it appears to us as a definite element, which exists in all the
worlds of which we have spoken. At the moment we are concerned with that
manifestation of it which we find in the highest subdivision of the
physical world. Just as the blood circulates through the veins, so does the
vitality circulate along the nerves; and precisely as any abnormality in
the flow of the blood at once affects the physical body, so does the
slightest irregularity in the absorption or flow of the vitality affect
this higher part of the physical body.

Vitality is a force which comes originally from the sun. When an ultimate
physical atom is charged with it, it draws round itself six other atoms,
and makes itself into an etheric element. The original force of vitality is
then subdivided into seven, each of the atoms carrying a separate charge.
The element thus made is absorbed into the human body through the etheric
part of the spleen. It is there split up into its component parts, which at
once low to the various parts of the body assigned to them. The spleen is
one of the seven force centres in the etheric part of the physical body. In
each of our vehicles seven such centres should be in activity, and when
they are thus active they are visible to clairvoyant sight. They appear
usually as shallow vortices, for they are the points at which the force
from the higher bodies enters the lower. In the physical body these centres
are: (1) at the base of the spine, (2) at the solar plexus, (3) at the
spleen, (4) over the heart, (5) at the throat, (6) between the eyebrows,
and (7)