Possession by spirits is one form of a whole range of human interaction with incorporeal intelligences. None of these types of interaction is necessarily dangerous. All types occur frequently to ordinary people, but those affected are usually unaware of the true nature of their experience.

At the bottom end of the scale is spirit perception. You may see a spirit in your dreams, and mistake that being for a dream character. Interaction is possible. The spirit may talk to you, and if it is mischievous or malicious it may try to torment you. Spirits are different from dream characters in that they take over the story of the dream and move it their own way. Often you will find yourself forcing yourself awake if the interaction with the spirit is unpleasant. In dreams, spirits can put on the characters of the dream like suits of clothing. But since these characters are not their real personalities, they often behave in ways the dream character would not.

Another type of spirit perception is to see a ghost while you are awake. Ghosts are not the souls of dead human beings, they are spirits who have put on the forms of dead human beings for the purpose of interacting with your consciousness. Spirits are very obliging. If you treat a spirit as the soul of your departed grandmother, for example, the spirit playing the part will do its best to behave as it thinks you want it to behave.

Spirits sometimes cause you to perceive them by touching you. The touch of a spirit on your body is usually cool, and is often mistaken for a draft. It can also be ticklish, and feels something similar to an insect crawling across your skin. More rarely, the touch of a spirit on your skin is warm, and feels like a heat pad. At times it takes the form of a pricking sensation, like being pricked with a needle. This pricking happens most commonly in the tips of the extremities, the fingers and toes -- hence Shakespeare's line in Macbeth "By the pricking of my thumbs, something wicked this way comes." I've frequently felt this pricking sensation on the tips of my big toes. One possibility is that it serves as the access point for the spirit to enter the body. More commonly spirits access the body through the mouth, nose, ears, anus, genitals, or top of the head.

The touch of a spirit can be felt on the surface of the skin. At these times it often feels exactly like the touch of a human hand. It can also be felt inside the body on the internal organs. Spirits can caress your heart, your brain, and other organs. They can also be perceived at times in the nerves of the teeth, which ache slightly when influenced by an incorporeal intelligence. When a spirit is in contact with your face, you may experience difficulty breathing. It is as though the body of the spirit thickens the air slightly. This can trigger mild asthma attacks in those who suffer from asthma.

At a higher level of communication, spirits may be deliberately invoked or evoked. Invocation is used to call a spiritual being into your body, or into the magic circle during rituals of invocation (the magic circle is an extension of the circle of your own skin). This is done when we wish to gain an intimate communion with a god or higher spirit for the purposes of taking on some of the qualities of that being. Sometimes spirits are invoked during magic because the magician wishes to assume the identity, and thus the occult authority and power, of the spirit for the purposes of the ritual. During ritual invocation we usually retain our self-awareness. We feel ourselves as both the spirit who has been invoked, and as our magical selves (the persona we adopt during rituals of ceremonial magic). We are thus twofold in consciousness during successful invocation.

You only invoke benign spirits of a higher order who are unlikely to make mischief while in partial possession of your mind and body. If, as sometimes happens, it is necessary to deal with lower spirits who may be hurtful, you always evoke them outside the bounds of the magic circle. Spirits are usually evoked into a triangle, which is drawn or otherwise marked on the floor just beyond the limit of the similarly marked magic circle. The point of the triangle points away from the circle, and points in the direction of the compass from which the lower spirit is to be summoned.

Usually, but not always, evoked spirits can be perceived in some way. Smoke or steam may be used to give them temporary bodies within the triangle. Or a magic mirror may be set within the triangle within which the spirit can manifest itself. The spirit may cause loud sounds outside the circle -- very loud knocks or cracks elsewhere in the house, or the sound of thunder, or sounds like furniture crashing to the floor. At a very high level of magic, the evoked spirit has a visible body, and can talk to the magician, but this is not the norm. Those who evoke a lower spirit and expect to see it standing within the triangle and to talk to it as they would converse with another human being are mistaking the legends and fables of evocation for the reality of evocation. Myths are always true, but their truth is symbolic.

Higher spirits are sometimes called angels, especially by magicians with a Christian heritage. Lower spirits are sometimes called demons. In actuality, there is no clear dividing line between good and bad spirits. The personalities of spiritual beings have the same broad range as the personalities of human beings. Some are very bad, or very good. Most are somewhere in between, neither wholly good nor wholly evil. As a general rule of magic, it is best to evoke all spirits not of a very high order. Unless you know that the spiritual being is responsible and benign, always evoke.

Possession, as the term is generally understood, involves the entrance of a spirit into the body and mind of a human being, in which the consciousness self-awareness of the human being is temporarily, or permanently, rendered unconscious, as it is during deep, dreamless sleep. The consciousness of the spirit takes over the motor control of its human host. In effect, the spirit pushes out the human soul and takes possession of its body, just as we would evict tenants from an apartment and assume residence there. In Voudoun (Voodoo) possession by spirits and gods is a necessary part of religious practice. The spirit or loa is said to "ride" the body of the possessed person the way a man rides a horse.

The reality of possession is that the human consciousness is seldom completely excluded. Usually the human consciousness goes into a kind of trance state in which it has no will. Such possessions happen to everyone, and usually are of short duration. We can recognize when a spirit has possessed us by our behavior. When we find ourselves doing things we would not normally do, things we would not like doing, especially things that seem bizarre or destructive or just plain disgusting, we are probably being possessed by some low spirit that is amusing itself at our expense.

This possession is made much easier when we are under the influence of alcohol or drugs, which tend to weaken our will. Almost all the horrible, shocking and pointless crime in the world is committed by low spirits possessing the bodies of human beings. Remember back to the last time you did something during sex for which you will be ashamed for the rest of your life -- you were almost certainly possessed at the time.

During this type of possession, our consciousness is made passive in exactly the same way it is subdued during hypnosis. However, it is the lower spirit who gives us suggestions rather than a hypnotist. There is a common cliché that a hypnotized person cannot be made to do anything he or she does not wish to do. This is not accurate. It depends on the circumstances, and the level of will in the hypnotized person. Just as you may be able to resist the directives of a hypnotist when you are given a suggestion you dislike, you may be able to resist the urgings of a spirit who possesses you -- or, if you are weak-willed, morally bankrupt, or intoxicated, you may not be able to resist.

Serious cases of possession occur when a strong spirit seeks to totally control the life of a human being, in effect to take over and experience that life as its own. This requires a great deal of effort and concentration on the spirit's part. Most low spirits are not capable of such effort. In such full blown cases of possession, the consciousness of the human involved may lie dormant for months or years. If the spirit has any degree of intelligence, it can hold possession of a person without giving other human beings any sign that it is in possession. Only spirits of a very low order are stupid enough to make the possessed individual foam at the mouth or roll around on the floor. An evil spirit of a slightly higher order will be more subtle, and will take its pleasure in more discrete, or at least more hidden, ways.

You may know individuals who have been under the complete domination of a spirit for years, and have no trace of their true human personality remaining. If the possessing spirit is clever, you will not be able to prove that possession has occurred. The spirit will pretend to be the person whose body it has taken over. The only hint will be that the person has undergone at some point in the past a complete change in personality. In effect, he or she will at some time have become a totally different person.

Good spirits of a higher order also possess humans. This occurs most frequently when the spirit wishes to communicate with humanity, and possesses an individual to use the voice of that person as its instrument of communication. Trance mediums and channelers have their personalities displaced by spirits on a regular basis. The prophets of the Bible were possessed by the Spirit (actually, the spirits) of God so that they could deliver their prophetic utterances.

Possession is not in itself harmful. It is not even unusual. It is only destructive when done by a destructive being for hurtful purposes. Good spirits or angels occasionally possess a person permanently when the consciousness of that person fails, or that person loses all will to live. These possessions are known as "walk-ins" because the spirit literally walks into the body of the despairing individual the way a man might walk into an empty house to take possession of it. In the case of walk-ins, the spirit generally tries to do good rather than evil. A profound change for the better will be observed in the personality of a walk-in. He or she will become kinder, more intelligent, more cheerful, more giving.

It is possible to drive possessing spirits out of a body. This cannot be done by subjecting the body to pain. The possessing spirit enjoys all strong sensations, including pain -- that is why possessed individuals are so often self-destructive. Exorcising a spirit must be done magically, by calling upon a higher authority to which the spirit is subject, and by erecting wards and boundaries that the spirit cannot cross. One approach is to bind the spirit into an inanimate object, and then to discard the object in some remote place where it will not be disturbed. This was the technique used by King Solomon, when he bound the evil spirits, or genii, into a brass bottle and cast the bottle into the sea (or by another account, into a deep lake). If this approach is used, be sure to put the object where no one will discover it by chance. There is a danger that anyone finding such a bound spirit may, without knowing what they are doing, release the spirit, and themselves become possessed by it.