The ancients described man as mind, body, and soul.
Psychologists of the twentieth century added the subconscious to that definition. This produces a four-fold (multiple) classification. The universe is also divided into four corresponding parts; worlds; as shown below:
WORLD BODY QUALITY
*Spiritual World *Spiritual Body (Soul or Kia) *Intuition (Instincts)
*Mental World *Mental Body (Conscious Mind) * Rational Thought
*Astral World *Astral Body (Subconscious) *Emotions
*Physical World *Physical Body *Physical Senses
The astral body (subconscious) is the intermediary for intuition, magickal and physical phenomena, and is the 'psychic link' to the physical world. Most occult and magickal phenomena originate in the invisible, non-insensate, non-physical realm (ie. Without physical senses). Each of the four worlds interacts with the other worlds. Psychic energy flows from the spiritual to mental to astral to physical. The physical world is a....projection or manifestation; reflection, or shadow of the higher worlds.
Our center consciousness is generally within these higher worlds. There are many similar terms used by other occult groups. For example, 'astral light' is another name of astral world, although it may sometimes also refer to the entire non-physical realm, as many 'inner planes' or 'the invisible world'. Planes are essentially the same as worlds.
When itinerant through a plane you can reach any terminus. We travel within the psyche (subconscious) of our minds, we choose to conceive whatever is essential. In truth, the human race is very naive, and their naivety leads them to worlds where nothing exist. Likewise, transportation to such universes is non-probable under the influence of such beliefs.
Credit to myself and K. Amber