I'm not sure what 3E has done with the shadow plane (I get annoyed and stop reading), but in 2E Oralpain has it right. The Inner Planes are connected to the Prime by the Ethereal, and the Outer Planes are connected to the Prime by the Astral. Despite the fact that both the Astral and Ethereal connect to the Prime at all points, they never connect with each other.
In 3.5e ethereal plain and astral plain remain unconnected. Each plan has his own ethereal plane. When using spells to planar travel one always uses the astral plane. Strangely enough there are also portals on the ethereal to everywhere, though only more scares then the astral plane. The shadow plane is alike the ethereal plane connected only to one plane. Unless you use the
'Deep Shadow' option.
Hope I said this all correct, as this is done by heart.
I can look at the exact descriptions if you wish and even find the exact terms for the 'connection' between the ethereal plane and astral, I believe it is coexistence. On the other hand, I do not think this discussion needs to become about 3.5 rules.
Still modding the Mod for the Wicked... It is a big project you know... And I got sidetracked (several times) a bit... sorry.
However, as we all know, Evil never really sleeps.
Sentences marking (my) life:
Winds of change... Endure them, and in Enduring grow Stronger
It takes a fool to look for logic in a man's heart
Never question the sanity of the insane
The Harmony of Life is Chaos
Living on Wings of Dreams
(1st march 2009) SHS women over me:
Kat: if there were more guys that looked like you out here, people's offspring wouldnt be so damn ugly
Noctalys: you are adorable
~~ I love it, and I am humbled! Yay! ~~