Returning to the consideration of these subplanes, and numbering them from the highest and least material downwards, we find that they naturally fall into three classes, divisions 1, 2 and 3 forming one such class, and 4, 5 and 6 another, while the seventh and lowest of all stands alone. The difference between the matter of one of these classes and the next would be commensurable with that between a solid and a liquid, while the difference between the matter of the subdivisions of a class would rather resemble that between two kinds of solid, such as, say, steel and sand. Putting aside for the moment the seventh, we may say that divisions 4, 5 and 6 of the astral plane have for their background the physical world in which we live, and all its familiar accessories. Life on the sixth division is not unlike our ordinary life on this earth, minus the physical body and its necessities; while as it ascends through the fifth and fourth divisions it becomes less and less material, and is more and more withdrawn from our lower world and its interests.
The scenery of these lower divisions, then, is that of the earth as we know it; but in reality it is also much more: for when we look at it from this different standpoint, with the assistance of the astral senses, even purely physical objects present quite a different appearance. As has already been mentioned, one whose eyes are fully opened sees them, not as usual from one point of view, but from all sides at once—an idea in itself sufficiently confusing. When we add to this that every particle in the interior of a solid body is as fully and clearly visible as those on the outside, it will be comprehended that under such conditions even the most familiar objects may at first be totally unrecognizable. Yet a moment's consideration will show that such vision approximates much more closely to true perception than does physical sight. Looked at on the astral plane, for example, the sides of a glass cube would all appear equal, as they really are, while on the physical plane we see the further side in perspective—that is, it appears smaller than the nearer side, which is a mere illusion. It is this characteristic of astral vision which has led some writers to describe it as sight in the fourth dimension—a suggestive and expressive phrase.
In addition to these possible sources of error, matters are further complicated by the fact that this higher sight cognizes forms of matter which, while still purely physical, arc nevertheless invisible under ordinary conditions. Such, for example, are the particles composing the atmosphere, all the various emanations which are always being given out by everything that has life, and also four grades of a still finer order of physical matter which, for want of more distinctive names, are usually described as etheric. The latter form a kind of system by themselves, freely interpenetrating all other physical matter; and the investigation of their vibrations and the manner in which various higher forces affect them would in itself constitute a vast field of deeply interesting study for any man of science who possessed the requisite sight for its examination. Even when our imagination has fully grasped all that is comprehended in what has already been said, we do not yet understand half the complexity of the problem; for besides all these new forms of physical matter we have to deal with the still more numerous and perplexing subdivisions of astral matter. We must note first that every material object, every particle even, has its astral counterpart; and this counterpart is itself not a simple body, but is usually extremely complex, being composed of various kinds of astral matter. In addition to this each living creature is surrounded with an atmosphere of its own, usually called its aura, and in the case of human beings this aura forms of itself a fascinating branch of study. It is seen as an oval [ovoid] mass of luminous mist of highly complex structure, and from its shape has sometimes been called the auric egg.
Theosophical readers will hear with pleasure that even at the early stage of his development at which the pupil begins to acquire this fuller sight, he is able to assure himself by direct observation of the accuracy of the teaching given through our great founder, Madame Blavatsky, on the subject of some at least of the "seven principles of man". In regarding his fellow-man he no longer sees only his outer appearance; almost exactly coextensive with that physical body he clearly distinguishes the etheric double; while the vitality (called in Sanskrit prana) is also obvious as it is absorbed and specialized, as it circulates in rosy light throughout the body, and as it eventually radiates from the healthy person in its altered form.
Most brilliant and most easily seen of all, perhaps, though belonging to a more refined order of matter—the astral—is that part of the aura which expresses by its vivid and everchanging flashes of colour the different desires which sweep across the man's mind from moment to moment. This is the true astral body. Behind that, and consisting of a finer grade of matter again - that of the form-levels of the mental plane—lies the mental body or aura of the lower mind, whose colours, changing only by slow degrees as the man lives his life, show the trend of his thoughts and the disposition and character of his personality. Still higher and infinitely more beautiful, where at all clearly developed, is the living light of the causal body, the vehicle of the higher self, which shows the stage of development of the real ego in its passage from birth to birth. But to see these the pupil must have developed the vision of the levels to which they belong. It will save the student much trouble if he learns at once to regard these auras not as mere emanations, but as the actual manifestation of the ego on their respective planes—if he understands that this is that ego which is the real man, not the various bodies which on the lower planes represent him.
So long as the reincarnating ego remains upon the plane which is his true home in the formless levels, the vehicle which he inhabits is the causal body, but when he descends into the form-level he must, in order to be able to function upon them, clothe himself in their matter; and the matter that he thus attracts to himself furnishes his mind-body. Similarly, descending into the astral plane he forms his astral or desire-body out of its matter, though still retaining all the other bodies, and on his still further descent to this lowest plane of all the physical body is formed according to the etheric mould supplied by the Lords of Karma. Fuller accounts of these auras will be found in my book Man, Visible and Invisible, but enough has been said here to show that as they all occupy the same space, the finer interpenetrating the grosser, it needs careful study and much practice to enable the neophyte to distinguish clearly at a glance the one from the other. Nevertheless the human aura, or more usually some one part of it only, is not infrequently one of the first purely astral objects seen by the untrained, though in such a case its indications are naturally likely to be misunderstood.
Though the astral aura from the brilliancy of its flashes of colour may often be more conspicuous, the nerve-ether and the etheric double are really of a much denser order of matter, being within the limits of the physical plane, though invisible to ordinary sight. If we examine with psychic faculty the body of a newly-born child, we shall find it permeated not only by astral matter of every degree of density, but also by the several grades of etheric matter. If we take the trouble to trace these inner bodies backwards to their origin, we find that it is of the latter that the etheric double—the mould upon which the physical body is built up—is formed by the agents of the Lords of Karma; while the astral matter has been gathered together by the descending ego, not consciously, but automatically, as he passes through the astral plane. (See Manual No. IV, p.44)
Into the composition of the etheric double must enter something of all the different grades of etheric matter; but the proportions may vary greatly, and are determined by several factors, such as the race, sub-race, and type of a man, as well as by his individual karma. When it is remembered that these four subdivisions of matter are made up of numerous combinations, which, in their turn, form aggregations that enter into the composition of the "atom" of the so-called "element" of the chemist, it will be seen