Mouseferatu said:
Assuming the standard D&D cosmology--that is, the Great Wheel or Planescape model--we know where souls go after they die. But where do they come from? Is there a particular plane? Positive Energy, perhaps? Are they created by the gods at the time of conception or birth? [...] Do they come from the Upper Planes, since newborn souls are (presumably) pure?
To some degree, D&D suffers from the fact that it draws information from several incompatible source traditions. On the one hand, it has Clerics who come from a quasi-Medieval Christian tradition (more clear in earlier editions) which have spells like Raise Dead and Resurrection. On the other hand, it has Druids who come from quasi-Celtic (or even quasi-New Age) tradition that has the spell Reincarnate. On the third hand, it has a popular Mythology set of Outer Planes inhabited by quasi-Norse gods, quasi-Greek gods, quasi-Egyptian gods and even quasi-Judeo-Christian devils and demons. And along with all of that, there is an alignment system that (by 3e) tries to stay agnostic on the issue of whether Evil is nature or nurture.
Basically, I think there just isn't one coherent cosmology at work here. Some source traditions have a soul take a one way trip while other source traditions have a recycling of souls. And if I remember correctly, the early D&D Elves and some other creatures had spirits and not souls and could be reincarnated but not raised or resurrected, which was yet another way to split things.
In my current campaign, I'm trying to sort out how I want to handle this so I can create a revision. With respect to the start of life, I've decided that a pregnant woman (and this is an issue in my current campaign) is "one body, two souls" for the purpose of magic. That means that if she's transformed, teleported, or whatever, the woman and her child are "one body" but if she dies, you'll need two Raise Deads or Resurrections to get her and her child back, otherwise it will be stillborn.
I'm also trying to figure out how various spells that can raise the dead after years might work in a setting with reincarnation. If you recall a soul back to its former body, does the current body suddenly drop dead when the soul is pulled out, if it opts to go?
The way I'm currently handling the migration of souls is that it can be a one way trip
or a two way trip. When you die, you go to the Outer Plane (I have only one, with regions spread across the inside of a sphere roughly corresponding to the Great Wheel planes but connected). If you drink from the Lethe River, you loose all memory of your past life and your soul is free to migrate back to the Prime Material plane to be reborn, otherwise you can stay on the Outer Plane. The catch is that the Lethe divides the Neutral middle from the Good "North" while the Acheron divides the Neutral middle from the Evil "South" and is very difficult to cross (you pay the ferryman as your ticket
out of Hell more often than into it).
So if you are Evil, your soul will go to the appropraiate Evil region and you'll have a very long and difficult journey of repentence to get to yourself back to the Prime Material plane where you will have another shot at an afterlife (you won't get into Heaven as an Evil soul) while if you are Good, you have no immediate reason to leave and plenty of reasons to stay. Good and Evil do fight over the Neutral middle, helping and harassing the souls and Outsiders there, and the Neutral middle is neither Heaven nor Hell, thus many Neutral souls will find themselves at the Lethe at some point, tempted to give their soul a shot at something different.
Many of the Good Outsider believe that the "end game" is for all of the souls to ultimate migrate into Heaven through atonement and reincarnation (perhaps even the Evil Outsiders according to some, though others think they will be left behind without any souls to prey on), which gives the Good some incentive to stay in Heaven. Evil Outsiders, on the other hand, enjoy their vices so have a vested interest in keeping souls from escaping and corrupting those in the Prime Material. And nobody really knows where the new souls come from, though I like that Postive Energy plane concept a bit.
I haven't fully sorted all of this out so thoughts or suggestions are welcome. Ultimately, I want my Good clerics to believe in an "end game" scenario where Good prevails while having Druids with a "circle of life" philosophy that wants to preserve the cycles of life and Evil with a vested interest in corruption and retaining those it has corrupted. Basically, I want multiple traditions that make a certain amount of sense from their own perspective because, given that D&D allows characters to talk to Outsiders and travel to the Other Plane, total ignorance or nothing but faith are not options, in my opinion.