The concept of Astral projection has been around for thousands of years, dating back to ancient China. It is currently often associated with the New Age movement.
There are two general schools of thought on the nature of astral projection; these can broadly be defined as the mystical model and the phasing model.
The mystical model includes a large variety of belief systems and astral maps, but they are tied together by their belief that astral projection takes place outside of the actual physical body. A more subtle energy body is believed to carry the consciousness outside of the physical body, and as one progresses to more advanced levels of the astral plane, more subtle bodies are realized and consciousness is transferred in turn to each of them (other mystical models assume only one subtle body). The subtle body is attached to the physical body by means of an energetic connection which usually takes the appearance of a silver cord "plugging" into the chakras like an umbilical cord.
The phasing model, which was defined by Robert Monroe, contains the belief that it is impossible to actually leave the body in the truest sense of the word, and that the astral planes and the physical world are merely points on the long spectrum of consciousness. When a person projects, they actually "phase" into another area of consciousness and the locales it contains. This can be likened to tuning a radio to another station. One of the initial signposts representing a phase shift away from physical reality has been labelled the state of focus 10 (mind awake/body asleep). This viewpoint can be seen as a logical progression of the philosophy that external reality is actually an internally created state.
Books about astral projection:
