I had a plan to do a big post about my ideas for a Spirit World as an alternative to the usual cosmologies...

But I ran into a couple snags.

1. I was having an unusually hard time articulating what I was trying to say
2. Almost all my ideas hewed pretty close to the section of the same name in the 3.x Manual of the Planes's "Alternate Cosmologies" chapter. The only new things I had was the idea of the souls of the dead crossing a bridge in the ethereal plane which spanned the Abyss and maybe some vague beginnings of an idea about astral travel, and I only had a handful of mechanical differences in mind.

With that in mind it might just be logical to share the relevant page (because that's all the description takes up) of that book. Surely slightly less than one page is little enough to amount to fair use.

THE REMAINDER OF THIS POST IS NOT OPEN CONTENT, BUT AN EXCERPT FROM MANUAL OF THE PLANES (c) WIZARDS OF THE COAST, PROTECTED UNDER FAIR USE

SPIRIT WORLD
The Spirit World is a realm brought into sharp focus. Colors are brighter, sounds more distinct, and every sense is more keenly aware of its surroundings. Some of its denizens say that the Material Plane is just a pale reflection of the Spirit World’s vibrancy. It is a dimension of ultimates.
The Spirit World is part of a cosmology radically different from the Great Wheel. In this cosmology, there are spirits for everything, from the greatest mountain to the smallest flower, as well as spirits of ancestors and objects long passed into history. The Spirit World is the plane where the spirits of all things, living and unliving, make their homes.
The Spirit World is a Transitive Plane that replaces the Astral Plane of the D&D cosmology. Unlike that plane, the Spirit World is both coexistent with and coterminous to the Material Plane, matching its terrain. A valley in the Spirit World corresponds to a valley on the Material Plane, and where there is a waterfall in one, there is a waterfall in the other. In the case of the Spirit World, however, the waterfall is higher, its water more pure, and its sound more pleasing than that of its equivalent on the Material Plane. The Spirit World’s waterfall would likely be the home of a water elemental that serves as the spirit of the waterfall.
Living creatures and their structures, from beaver dams to palaces, do not necessarily have direct analogs. However, where a citadel stands on the Material Plane, a similar citadel (though greater and stronger) may stand in the Spirit World, occupied by the spirits of revered ancestors of the Material Plane citadel’s ruler.
SPIRIT WORLD TRAITS
The Spirit World has the following traits:
• Normal Gravity.
• Timeless: In the Spirit World, creatures do not hunger, age, or thirst. Days and nights pass within the Spirit World as they do on the Material Plane. However, the nights are ebony black and set with brilliant stars, while great clouds arching across a sky of purest
blue dominate the days.
• Infinite Size: Unless the Material Plane has the finite size trait, in which case the Spirit World does too.
• Alterable Morphic: Changing things in the Spirit World does not directly affect the Material Plane, and changes on the Material Plane aren’t necessarily reflected in the Spirit World right away.
• No Elemental or Energy Traits: However, particular locations within the plane may have those traits. A smith’s forge on the Material Plane, for example may have an equivalent in the Spirit World with the fire-dominant trait.
• Mildly Neutral-Aligned: Specific locations may have other alignments; the Spirit World equivalent of a haunted graveyard might be mildly evil-aligned, for example.
• Enhanced Magic: All divine spells are extended and empowered on the Spirit World. Arcane magic, which comes from knowledge as opposed to proper veneration,
is unaffected.

SPIRIT WORLD LINKSThe Spirit World is coexistent with the Material Plane, and movement on one is equal to movement on the other. A traveler who enters the Spirit World, walks three miles north, and then returns to the Material Plane is three miles north of the walk’s starting point.
Travelers reach the Spirit World through the Ethereal Plane, which forms a border region between the Material Plane and the Spirit World. A character on the Ethereal Plane can see onto both the Material Plane and the Spirit World: the Material Plane clearly and the Spirit
World as a faint echo. By concentrating on the echo, a traveler can move to the far side of the Ethereal Plane and enter the Spirit World.
Because the Spirit World replaces the Astral Plane, spells that allow access to the Astral Plane use the Spirit World instead.
The Plane of Shadow does not connect to the Spirit World, so spells that use the Plane of Shadow do not function in the Spirit World.
The Spirit World leads to other planes, in particular the homes of whatever great powers oversee the operation of the known universe. A traveler through the Spirit World finds portals to the great palaces of these deities, as well as unique heavens and hells. A traveler seeking the Duke of Storms, for example, would find a portal to his palace occupying the same general location as storm-wracked peaks on the Material Plane.
SPIRIT WORLD INHABITANTS
The Spirit World is home to a variety of creatures, including fey, elementals, undead, outsiders, and dragons. Those with access to the plane shift spell visit the Material Plane under their own power, and spellcasters use summoning spells to bring other Spirit World creatures to the Material Plane. Still other Spirit World creatures find natural portals between the planes.
FEATURES OF THE SPIRIT WORLD
Settled areas of the Material Plane are particularly dangerous in the Spirit World, because these places are where the spirits of ancestors dwell. These spirits are extremely protective of their descendants; an assassin who pops into the Spirit World to infiltrate a local duke’s reception hall will be confronted by one or more ghosts of the duke’s predecessors. This is one reason that rulers live in the same palace for generations: They enjoy the protection of their ancestors.