part in its life and are of equal importance, to it.

We usually speak of the invisible part of the physical body as the etheric double; "double" because it exactly reproduces the size and shape of the part of the body that we can see, and "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 æther 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) at the top of the head. There are other dormant centres, but their awakening is undesirable. The shape of all the higher bodies as seen by the clairvoyant is ovoid, but the matter composing them is not equally distributed throughout the egg. In the midst of this ovoid is the physical body. The physical body strongly attracts astral matter, and in its turn the astral matter strongly attracts mental matter. Therefore by far the greater part of the matter of the astral body is gathered within the physical frame; and the same is true of the mental vehicle. If we see the astral body of a man in its own world, apart from the physical body we shall still perceive the astral matter aggregated in exactly the shape of the physical, although, as the matter is more fluidic in its nature, what we see is a body built of dense mist, in the midst of an ovoid of much finer mist. The same is true for the mental body. Therefore, if in the astral or the mental world we should meet an acquaintance, we should recognise him by his appearance just as instantly as in the physical world. This, then, is the true constitution of man. In the first place he is a Monad, a Spark of the Divine. Of that Monad the ego is a partial expression, formed in order that he may enter evolution, and may return to the Monad with joy, bringing his sheaves with him in the shape of qualities developed by garnered experience. The ego in his turn puts down part of himself for the same purpose into lower worlds, and we call that part a personality, because the Latin word _persona_ means a mask, and this personality is the mask which the ego puts upon himself when he manifests in worlds lower than his own. Just as the ego is a small part and an imperfect expression of the Monad, so is the personality a small part and an imperfect expression of the ego; so that what we usually think of as the man is only in truth a fragment of a fragment. The personality wears three bodies or vehicles, the mental, the astral and the physical. While the man is what we call alive and awake on the physical earth he is limited by his physical body, for he uses the astral and mental bodies only as bridges to connect himself with his lowest vehicle. One of the limitations of the physical body is that it quickly becomes fatigued and needs periodical rest. Each night the man leaves it to sleep, and withdraws into his astral vehicle, which does not become fatigued, and therefore needs no sleep. During this sleep of the physical body the man is free to move about in the astral world; but the extent to which he does this depends upon his development. The primitive savage usually does not move more than a few miles away from his sleeping physical form--often not as much as that; and he has only the vaguest consciousness. The educated man is generally able to travel in his astral vehicle wherever he will, and has much more consciousness in the astral world, though he has not often the faculty of bringing into his waking life any memory of what he has seen and done while his physical body was asleep. Sometimes he does remember some incident which he has seen, some experience which he has had, and then he calls it a vivid dream. More often his recollections are hopelessly entangled with vague memories of waking life, and with impressions made from without upon the etheric part of his brain. Thus we arrive at the confused and often absurd dreams of ordinary life. The developed man becomes as fully conscious and active in the astral world as in the physical, and brings through into the latter full remembrance of what he has been doing in the former--that is, he has a continuous life without any loss of consciousness throughout the whole twenty-four hours, and thus throughout the whole of his physical life, and even through death itself.