To the clairvoyant vision the prana-aura appears like the vibrating heated air arising from a fire, or stove, or from the heated earth in summer. If the student will close his eyes partially, and will peer through narrowed eyelids, he will in all probability be able to perceive this prana-aura surrounding the body of some healthy, vigorous person—particularly if the person is sitting in a dim light. Looking closely, he will see the peculiar vibratory motion, like heated air, at a distance of about two inches from the body of the person. It requires a little practice in order to acquire the knack of perceiving these vibrations—a little experimenting in order to get just the right light on the person—but practice will bring success, and you will be repaid for your trouble.
In the same way, the student may by practice acquire the faculty to perceiving his own prana-aura. The simplest way to obtain this last mentioned result is to place your fingers (spread out in fan-shape) against a black background, in a dim light. Then gaze at the fingers with narrowed eyelids, and half-closed eyes. After a little practice, you will see a fine thin line surrounding your fingers on all sides—a semi-luminous border of prana-aura. In most cases this border of aura is colorless, but sometimes a very pale yellowish hue is perceived. The stronger the vital force of the person, the stronger and brighter will this border of prana-aura appear. The aura surrounding the fingers will appear very much like the semi-luminous radiance surrounding a gas-flame, or the flame of a candle, which is familiar to nearly everyone.
Another peculiar phenomenon of the astral plane, perceived by clairvoyants of a certain degree of development, is that which is known as the "thought-form." A thought-form is a specialized grouping of astral substance, crystalized by the strong thought impulses or vibrations of a person thinking, or manifesting strong emotional excitement. It is generated in the aura of the person, in the first place, but is then thrown off or emitted from the atmosphere of the person, and is sent off into space. A thought-form is really but a strongly manifested thought or feeling which has taken form in the astral substance. Its power and duration depend upon the degree of force of the thought or feeling manifesting it.
These thought-forms differ very materially from one another in form and general appearance. The most common form is that of a tiny series of waves, similar to those caused by the dropping of a pebble in a pond of water. Sometimes the thought-form takes on the appearance of a whirlpool, rotating around a centre, and moving through space as well. Another form is like that of the pin-wheel fireworks, swirling away from its centre as it moves through space. Still another form is that of a whirling ring, like that emitted from a smokestack of a locomotive, or the mouth of a smoker—the familiar "ring" of the smoker. Others have the form and appearance of semi-luminous globes, glowing like a giant opal.
Other thought-forms are emitted in jet-like streams, like steam puffed out from a tea-kettle. Again, it will appear as a series of short puffs of steam-like appearance. Again, it will twist along like an eel or snake. Another time it will twist its way like a corkscrew. At other times it will appear as a bomb, or series of bombs projected from the aura of the thinker. Sometimes, as in the case of a vigorous thinker or speaker, these thought-form bombs will be seen to explode when they reach the aura of the person addressed or thought of. Other forms appear like nebulous things resembling an octopus, whose twining tentacles twist around the person to whom they are directed.
Each thought-form bears the same color that it possessed when generated in the aura of its creator, though the colors seem to fade with time. Many of them glow with a dull phosphorescence, instead of bright coloring. The atmosphere of every person, and every place, is filled with various thought-forms emanated from the person, or persons who inhabit the place. Each building has its own distinctive thought-forms, which permeate its mental atmosphere, and which are clearly discernible by trained clairvoyant vision.
I here take the liberty of quoting a few paragraphs from my little book entitled "The Astral World," in which the phenomena of the astral plane are explained in detail. I reproduce them here in order to show you what you may see on the astral plane when your clairvoyant vision is sufficiently developed to function there. The words are addressed to one who is sensing on the astral, plane.
"Notice that beautiful spiritual blue around that woman's head! And see that ugly muddy red around that man passing her! Here comes an intellectual giant—see that beautiful golden yellow around his head, like a nimbus! But I don't exactly like that shade of red around his body—and there is too marked an absence of blue in his aura! He lacks harmonious development. Do you notice those great clouds of semi-luminous substance, which are slowly floating along?—notice how the colors vary in them. Those are clouds of thought-vibrations, representing the composite thought of a multitude of people. Also notice how each body of thought is drawing to itself little fragments of similar thought-forms and energy. You see here the tendency of thought-forms to attract others of their kind—how like the proverbial birds of a feather, they flock together—how thoughts come home, bringing their friends with them—how each man creates his own thought atmosphere.
"Speaking of atmospheres, do you notice that each shop we pass has its own peculiar thought-atmosphere? If you look into the houses on either side of the street, you will see that the same thing is true. The very street itself has its own atmosphere, created by the composite thought of those inhabiting and frequenting it. No! do not pass down that side street—its astral atmosphere is too depressing, and its colors too horrible and disgusting for you to witness just now—you might get discouraged and fly back to your physical body for relief. Look at those thought-forms flying through the atmosphere! What a variety of form and coloring! Some most beautiful, the majority quite neutral in tint, and occasionally a fierce, fiery one tearing its way along toward its mark. Observe those whirling and swirling thought-forms as they are thrown off from that business-house. Across the street, notice that great octopus monster of a thought-form, with its great tentacles striving to wind around persons and draw them into that flashy dance-hall and dram-shop. A devilish monster which we would do well to destroy. Turn your concentrated thought upon it, and will it out of existence—there, that's the right way; watch it sicken and shrivel! But, alas! more of its kind will come forth from that place."
The above represents the sights common to the advanced occultist who explores the astral plane either in his astral body, or else by means of clairvoyant vision. To such a one, these sights are just as natural as those of the physical plane to the person functioning by ordinary physical senses. One is as natural as is the other—there is nothing supernatural about either.