pneuma

Pneuma is the theoretical source of all souls. Though evidence for it is indirect, it is largely accepted as the the truth due to its predictions matching all observations.

Fundamental Theory

Pneuma is the prevailing theory to explain souls. Scholars claim that there is a plane separate but connected to the Sora which contains the fundamental energy that generates souls. When a child is born, a soul is drawn from the pneuma through some mechanism and placed into the body of the newborn. These souls then give the individual the ability to develop a personality, feel emotion, and grow and develop mentally.
The souls are then able to provide worship and belief to the gods, who draw power from that belief. After death, the soul either passes to the afterlife according to their beliefs or wanders as a ghost after.

Theoretical Necessity

While most divine pantheons have deities responsible for creation, life, or birth, precious few have deities which claim domain over souls themselves. While most pantheons have psychopomps or chthonic gods who are responsible for souls after death, these deities only deal with souls after they have spent time inhabiting a mortal body. Thus there exists an open question on where souls come from.
Previously, it was believed that souls were a mixture of the fundamental energies, fuliginous and nivose. However, arcane research has shown that these energies can be directly manipulated and inserted into bodies, but do not create intelligent life. They can animate bodies and objects, and are important forces in necromancy and vitamancy. However, bodies empowered by pure fuliginous energy and constructs empowered by nivose energy are mindless, unable to learn, change their behaviors, or do anything beyond obey the commands of their creators. For centuries, it was assumed both energies needed to be mixed to create a soul, but recent arcane advancements have shown that a combination simply creates a facsimile of sapience, with constructs still unable to adapt, feel emotion, or learn.
Thus the necessity for a new source of souls was needed. The first new theories assumed they were the creation of the gods, perhaps as a joint effort. However, it is widely accepted that the gods require the belief of mortals to provide them with power, and that belief is not possible without possessing a soul. Indeed, it appears likely that the energy of the soul and the energy of belief is one in the same, as sufficient belief has been known to create a myriad of effects in the Sora. Thus, if the gods could simply create the energy they require, it would not make sense for them to bother with worshipers.
No material source of souls could be discovered, thus another plane providing the source of souls was theorized.

Experimental Evidence

No direct observation of the pneuma has ever been made. Requests to the gods for information have been ambiguous, with them neither confirming nor denying the theories. However, indirect evidence has been observed. It has long been known that mind reading magics and telepathy attempted with infants at the moment of birth fail, indicating the lack of a soul and mind. Sometime within the first ten minutes of life this changes and contact (albeit extremely basic) can be made. On rare occasions, contact seems to have been made exactly at the moment the newborn gains sapience, as the mind readers have experienced a brief, overwhelming flood of thoughts and images. This is claimed to be the moment the pneuma opens and a soul emerges from it.
When the Álfuríki god Odr was slain, the mortals who witnessed it all experienced a brief flood of memories and thoughts they claimed did not belong to them, then saw the sky briefly become a strange color they claimed to have never seen before, though none were able to describe it. Proponents of the pneuma theory believe this was the collected belief in the god flooding those present then disappearing into the pneuma.

Criticism

While most scholars believe pneuma theory is accurate, a minority believe it fails to adequately explain the origin of souls. The largest objection is that an alternate plane of existence only shifts the origin of souls elsewhere and does not solve the problem of how the souls are created. Additionally, it is thought unlikely that there would only be one additional plane of existence; either the Sora is the sole, unique plane or there are innumerable planes of existence. Since no other aspect of reality requires the existence of another plane, it does not make sense that souls should either.
The evidence is dismissed as well. The readings from newborns has been dismissed as both mistakes of the mind readers, since it cannot be reliably reproduced, and inconclusive regardless, as there are numerous other explanation for the images, such as prophecy, visions of the child's possibilities, and even the newborn's mind recovering from the trauma of birth. The experiences of those who witnessed the death of Odr are thought to be hallucinations brought on by the horror of witnessing an immortal being die.
Finally, what some consider to be the strongest evidence against it is the fact that the Dranomyr Archive dismisses the theory. While they offer no alternate theory, claiming the other empires are "not ready for the truth", they also state they previously had a similar theory that they later rejected.

Type

Metaphysical, Divine