In order to perform any kind of magic, from folk magic spells to shamanic work to Qabalistic invocation, it's helpful to understand the magical theory of the nature of reality. These are some of the things you might expect to experience in your shamanic journeys to the other worlds, or in dreams, visions, and meditations.  For our purposes reality consists of several dimensions, or density degrees (or planes of existence) which coexist. For convenience I'll call them the Physical Plane, the Etheric Plane, the Astral Plane, the Mental Plane, the Idea Plane, the Spiritual Plane, the Nirvanic Plane and Akasha (the First Principle.)  Other people may call them differently.

Here is a brief overview:

The Physical Plane

      I see no need to discuss the Physical Plane since we live work and play in it every day. Simple observation should be enough.

The Etheric Plane

      The next plane is one I'll call the Etheric Plane. Like the Physical Plane, the Etheric Plane is limited in both time and space. Objects and entities of the Etheric Plane have the same shape and occupy the same space as objects and entities of the Physical Plane. Entities on the Etheric Plane do not have an independent existence from their physical counterpart. The appearance of objects and entities on the Etheric Plane is a kind of indistinct gray of roughly the same shape as the physical object or entities.

      Some people, through years of training and intense concentration, are able to separate their Etheric Body (which contains their Astral, Mental, Ideal, and other subtle bodies) from their Physical body. An Etheric Body projected in this manner is able to travel in the corresponding Physical Plane, although not very far from the physical body. A projection of this sort could see what is going on some distance away in the physical world and retain memory of that observation upon return to the physical body.

      Some sensitive people, under some circumstances, can see an Etheric Body with their physical eyes. That which they see is either a projected Etheric body or what we call a ghost.

      When a person dies what happens is that the Etheric Body is permanently separated from the Physical body. Normally the deceased will stay near their physical body for a while before realizing what has happened. Often the person will go to their home or other familiar locations after that first separation. This is why their relatives and friends sometimes see them after their death. Sunlight weakens an unattached Etheric Body.

      Usually within about three days the Etheric Body is so weak the Astral Body separates from it and goes on to the Astral Plane. An explanation of that Plane is in the next section. This leaves the Etheric Body without intelligence, but with a vague impulse towards self-preservation. It is a shell; a shade; a ghost. In many ways that Etheric Body is an animated corpse. It will usually return to the vicinity of it's physical body where, since it cannot get the energy it needs to maintain existence, it stays while it gradually disintegrates.

      Sometimes, being attracted to the energy left behind, it will stay around where the person lived absorbing that energy and attaching itself to and feeding off of the life force of the people left behind and thus prolonging it's existence a little longer. Yet without intelligence its absorption of energy is haphazard and eventually it will disintegrate anyway.

      Sometimes it doesn't work that way. Under some circumstances the deceased refuses to accept that his or her physical body has ceased to function. That person may, by pure willpower, keep his Astral and Etheric bodies together. Without nourishment the Etheric body will disintegrate anyway, thus freeing the Astral. However an Etheric body inhabited by the Astral Body, maintains intelligence. It can discover how to intentionally attach itself to a living being and feed off of that beings energy. The more energy it absorbs, the stronger and more vital it feels. In this manner it becomes a vampire and can continue to "live" indefinitely.

The Astral Plane

      The next plane is the Astral Plane. In a sense the Astral Plane is the fourth dimension; bound to, but not limited to, space and time. Here is the origin of light, sound, color, rhythm, shape, and life. The landscape of the Astral Plane appears, in many ways, identical to the landscape of the Physical Plane, since it contains the Astral Bodies of all of physical existence. Every living being, every rock, every, plant, every river, ocean, mountain, and so forth that we are familiar with on the Physical Plane also exists, in it's natural state, in the same shape on the Astral Plane. However the material of the Astral Plane is more plastic than that of the Physical Plane and can be shaped by the power of will, although that shape will eventually return to it's natural appearance.

      In addition to the region corresponding with our Physical Plane, other regions can be found on the Astral. Here is where we will find the Upperworld and Lowerworld, the Abodes of the Dead, all of the Heavens, all of the Purgatories, all of the Hells of every philosophy that has existed.

      The inhabitants of the Astral Plane include our anthropomorphic concepts of Gods, Goddesses, Angels and Archangels, Devils and Demons, Power and Spirit Animals, "good and bad" spirits of various regions such as the planetary realms, Elementaries (which are Thoughtforms from the Mental Plane that have a condensed shape into the Astral Plane), "pure" Elementals of the Salamander, Sylph, Undine, and Gnome races, and beings such as fairies, pixies, nymphs, satyrs, centaurs, and so forth. Like humans, the above mentioned entities each have their own special talents and areas of expertise. Some can and do interface with different areas of the still more subtle Planes where they gather or manipulate information. Some can and do cause changes in the Astral matrix which will cause change in the Physical Plane.

      Here also exist Larvae, a sort of an Astral slug, created by and feeding off of emotions. These Larvae have no intelligence, but do have an instinct for self preservation, and are attracted to the emotion that brought them into existence. The feeding of one of these Larvae produces more of the emotion that created it, thus making it stronger. When the emotion is stilled, the Larvae will disintegrate.

      When a person's physical body dies and their Astral Body is released from it's Etheric Shell, the Astral Body then exists as an independent entity on the Astral Plane. The person then is drawn to that region of the Astral Plane, often a Heaven or a Hell, where they expected to go based upon the training and conditioning they had in physical life. There they remain until they realize that they do not need to have that experience any longer. Eventually a person's Astral Body will dissolve, leaving them in a density degree corresponding to their level of maturity until they choose to continue their development by experiencing another physical incarnation.

      With training a person can go into a deep trance, a shamanic ecstasy, and consciously project or separate their Astral Body from their physical body. During their projection their Astral body can explore any of the realms in the Astral landscape, and communicate with any of the inhabitants they encounter.

The Mental Plane

      The next plane is the Mental Plane. The Mental Plane is spaceless and timeless. It can be thought of as both a place and a doorway to other Planes of Existence. On this plane one can travel into the past and into the possibilities of the future. The landscape of the Mental Plane has numerous regions which are inhabited by various beings, depending upon their particular degree of "maturity". The material of the Mental Plane is fluid, flexible, changeable in appearance by thought itself. The Mental Plane is the world of Ideaforms, which have their own form, color, and vibration. Some of the other inhabitants are the more abstract concepts of Gods and Goddesses, the independent Mental Bodies of deceased people whose Astral Bodies have been dissolved by the Elements, and Thoughtforms, artificially created either intentionally or unintentionally by the intense thoughts of one or more humans. Thoughtforms are often created by a magician in order to accomplish some specific task which it will accomplish on the Mental Plane. A Thoughtforms strength depends upon the mental strength and abilities of it's creator(s). Thoughtforms differ from Ideaforms in that Thoughtforms have a quality of consciousness and an instinct for preservation. Because of this they can take on the appearance of an Ideaform.

      Of the lower three planes, The Mental Plane is the easiest one to travel and explore, though can be difficult to understand. The method is simply directed daydreaming. Here one can see a reflection of existence on the Astral Plane, although this reflection is usually seen distorted and unclear. Often a person who is wandering on the Mental Plane will mistake their Mental Wanderings for Astral Projection.

The Idea Plane

      The Idea Plane is the last subtle plane of existence that we can comprehend at this stage of our spiritual evolution. It is spaceless, shapeless, and timeless. It is within the Idea Plane that the Akashic Records can be found. It's useful to think of the Akashic Records as a Library which contains the Memory of All Past, the Record of All Present, and the Possibilities of All Future. In some ways this Plane could be thought of as similar to Jung's conception of a Collective Unconscious. The Idea Plane is the origin of all original abstract thought and ideas which may be perceived by people depending upon their readiness to receive them. Ideaforms, inhabitants of the Mental Plane, had their origin as these abstract thoughts in the Idea Plane. Inhabitants of the Idea Plane include those beings who have spiritually matured enough so that they may choose whether or not to incarnate in the Physical Plane.

The Spiritual Plane

      I have only glimpsed this plane. I do not have extensive personal experience of it. The Lords of Karma, Cause and Effect, are said to dwell here.

The Nirvanic Plane

      I have only glimpsed this plane. I do not have personal experience of it. I have had a "satori" experience which is said to be a dim reflection of the nirvanic experience. The Nirvanic Plane is said to be beyond the comprehension of any who are not experiencing it.

Akasha

      The First Principle is called Akasha. Akasha is spaceless and timeless; the inconceivable ultimate cause of all things existing and created. You would not be wrong to call it God or Divine Providence, though you would be wrong to personalize it as an anthropomorphic being. Since it contains within it both positive and negative, a developed mystic discovers that everything contains it's own opposite. Ultimately there is no such thing as good or evil, there is only existence. In truth Jehovah and Satan are merely two names for the same God. There can be no front without a back. There can be no inside without an outside.

      It's useful to think of Akashic material, which I should probably call "mana"  as being ultra fine and getting more and more concentrated and dense as its vibrations become the various planes of existence down to and including the physical plane. The planes of existence coexist as density degrees, one interpenetrating another. Akasha emanates, from it's own vibrations, the Elements which are the subtle building blocks of all existence. These pervade all of the planes of existence. The Oversoul.