Magicians are aware of three "realms" of existence. The first is the physical realm, our natural physical world, and all off its corresponding physical laws. On one "side" of us, we have the astral realm. The astral realm occupies the same "space" as the physical plane, but has different "physical" ("astral"?) laws. It is always there, right next door, just a step sideways. It thrives on life, and so emotion, thought, and spirit are emphasized on the astral. Whithout life, there is no astral space; and so without a thriving gaiasphere to sopport it, the astral plane does not extend into space.

 

pg.161