The Manifest Path/Souls
Souls clearly exist, and the use of blood sacrifice to power the Light's weapon against the abominations on Beluaterra proves this as the physical form of the blood cannot possibly provide enough energy to power such destruction. This also shows that losing blood also loses a part of your soul, though like blood this can be replenished. This makes the loss of blood a fairly important event, and explains why the sites of large battles often end up being revered as hallowed ground. This is not a blessing of the gods, but the presence of a large amount of spilled soul energy. This dissipates over time, back into the natural cycle, thus also explaining why battlefields become forgotten. This also explains bloodstained holy relics, depression as a result of blood loss (post-birth depression being a common example), and why children seem more attuned to their mothers (all their blood comes from their mother, and thus their souls as well, aside from a small spark provided by their fathers). Indeed, many facets of the world, including the pagan blood rituals, can be explained by this simple understanding.
This then leads to the question of what happens to a soul when someone dies. The path to the answer is found with the above discussion on the hallowed battlefields. What else is commonly felt to be hallowed, blessed by the gods? So-called holy sites, either pagan or shrines and temples. The exact mechanism for why souls are drawn to these structures is unknown.
The Light proved that souls have great destructive energy, but it is a long-established belief that hallowed grounds are protected from various spiritual interferences, thus signifying that these souls can serve a defensive purpose as well which would make sense. The Light is not creating energy, but merely finding a way to release all the power of a soul at once in a destructive fashion, and the power of souls and the hallowing of temples explains why they could only function in temples. This is further evidence that the Light is highly suspicious, as they are quite literally destroying the souls of those they claimed to want to save. Defensively, souls are much weaker, but of course last far longer. They still return to the natural cycle over time in a temple or shrine, but far more slowly as they are somewhat isolated from the rest of the world.
So what does all this mean? What does the soul imply for Walkers of the Path? It means that we must improve our souls even more than our bodies to assist us in our eternal war. Our souls are quite literally our best defenses. One may improve their soul by many means: Culture, arts, learning, training...Anything that improves your mind and spirit improves your soul. Thus, constant learning is the goal for a Walker. This is not, as some would have it, a selfish goal but an ultimately selfless goal, as the end result is better protection for your descendants.