Ethereal Plane

In the Great Wheel cosmology model, the Ethereal plane existed adjacent to the Prime Material Plane and connected it to the Inner planes (the Elemental planes plus the Energy planes). The Ethereal touched the Prime at all points that were located within crystal spheres through what was called the Border Ethereal. It was unknown whether the Border Ethereal touched the Prime in the phlogiston.   The non-Border region was called the Deep Ethereal. While in the Border Ethereal, a traveler could still see into the adjacent plane but only dimly and not very far, whereas those on the bordering plane could not see the traveler without magical detection. Verbal communication was not possible between the Border Ethereal and the bordered plane. The Ethereal was unique among the many planes in that an individual could exist in two planes simultaneously: the Border Ethereal and the adjacent plane.   When travelers crossed into the Border Ethereal, they and all their possessions were converted to their Ethereal equivalents—metal became ethereal metal, flesh became ethereal flesh, and so on —allowing free movement (in most cases) in any direction through the solid matter of the adjacent plane. Since everything was permeated with ethereality, an air-breathing creature could breathe ethereal air and could not drown in an ethereal lake nor be crushed by an ethereal rock. However, not all in the adjacent plane was insubstantial. Living things larger than one-celled animals generated an aura that radiated around them and prevented passage to their interior, so an ethereal traveler could not place a weapon inside a living creature where it would materialize and cause damage. A jungle would be an extremely torturous maze to navigate; it would be much easier to float above the vegetation or pass below its roots. Dense metals such as lead or gold also prevented passage of ethereal matter. And finally, some magic spells and alchemical mixtures could form an effective barrier.   Travel in the Ethereal and Border Ethereal was accomplished by force of will—you wished to go somewhere and you did, at your normal rate of movement. There was a sense of up and down but no real gravity existed. Objects released from possession would hover where they were dropped; it was impossible to fall in the Ethereal plane. To get to another plane, one had to pass through a curtain of vaporous color into the Deep Ethereal, then traverse that region until reaching the curtain that demarcated the Border Ethereal of the destination plane. Each Inner plane and demiplane had a curtain with a unique color. The Prime Material plane's curtain was turquoise.[15] If the (usually magical) ethereal effect wore off while a traveler was in the Deep Ethereal, he would immediately be forced through a random curtain at a random location in the Border Ethereal and deposited on the plane which it bordered.   By use of magic—or by the natural ability that some creatures, like phase spiders, were thought to have—one could fade into the Ethereal and travel at will. Gravity gave a sense of up and down, but movement in any direction was equally easy, and objects released hovered in place. The proto-matter swirling about the Ethereal plane could be used to create demi-planes, either through natural fluctuations in the medium or by the actions of powerful beings. Some known demi-planes included the Demi-Plane of Shadow, the Demi-Plane of Time, the Demi-Plane of Electro-Magnetism, and the possibly legendary Demi-Plane of Imprisonment. The Demiplane of Nightmares was also sometimes said to reside within the Ethereal plane, as was the Region of Dreams. There also existed a series of demiplanes in the Deep Ethereal known as the "mazes", sections of the city of Sigil spun off into the plane, that were created by the Lady of Pain to imprison all those who opposed her.   When you passed through a curtain into the Deep Ethereal, time slowed down to one tenth the rate it flowed in the Border Ethereal and the plane that it bordered. For every ten hours spent in the Deep Ethereal only one hour passed on the other side of the curtain. Metabolic and other natural processes slowed down also, so it did not feel like ten hours, when you crossed back through a curtain into a Border Ethereal you were only an hour older and an hour hungrier.   The Deep Ethereal swirled with large blobs of protomatter (imagine a cosmic lava lamp) which could form a demiplane when a critical size was reached. Powerful wizards, technologists, or demigods could also bend the proto-matter to their will and create a demiplane. These nascent planes might exhibit some of the characteristics of the Inner planes or the Prime, but with their own rules of gravity, material make-up, etc., and even support life. Most demiplanes eventually collapse into themselves and break up or merge with another Inner or Prime Material plane.