Thinking deep thoughts one day, I considered the question: 'What is the soul?'
The basic ideas usually related to this concept, regardless of culture, are that it is a unique part of each individual, and that it somehow survives beyond death, either reincarnating in another being or perhaps returning to some kind of 'god', who created the being in the first place.
I realised there is a parallel, of sorts, in nature.
We are born, shaped by DNA, but entirely unique beings. After we die, our uniqueness lives on, after a fashion, returning to the gene pool of the species and helping to shape new unique beings. DNA is the creator deity, the demiurge, and our uniqueness the soul, which does not truly perish when we are gone, but is 'reincarnated' in future generations.
On the other hand, it isn't merely the DNA we transmit to our children that shapes the future. Every action we perform is meaningful. They may seem insignificant at the time, but if enough individuals behave in a certain way, it will affect the direction the species will evolve in, thus again returning to the gene pool. It isn't restricted to biology, of course. We continuously shape the society and culture around us. It may not be our consciousness, as such, that lives on, but we do shape the future, and elements of us live on in it.
All of this requires, more than anything, interaction. If we neither have children, nor affect others in any way with our behaviour, our existence would be pretty meaningless.
So this is how I came to define the soul: it is the portion of a unique entity which interacts with the world around it, thus shaping the world and living on in the changes it brings about.
But, continuing this train of thought, I of course realised this does not only apply to human beings. All entities, living or inanimate, even abstract concepts and imaginary beings, shape the world through our interaction with them. Consider how gods have shaped entire civilisations, or even the effect fictional heroes, never claimed to be real, have had on modern society. Consider how one word, like 'love' or 'democracy' can change the world. The same applies to physical objects. Think of a world without a hammer, or pen, or computer. These things can be just as powerful, if not more so, than the actions of one 'real' individual. Our interactions with them shape the species, and the entire world, in the same way that our interactions with each other does.
There was a time I considered myself a pantheist. But I've come to feel that it is the individual that is most important, and the interaction between individuals. The 'small details' rather than a 'big picture' that we can never comprehend in its entirety anyway. Perhaps a form of animism is a better approach to this world than pantheism, after all.
I sometimes use the word kami for this conception of the soul, after the Shinto concept. It is not identical, of course, but I think it is probably one of the closest precedents found in the world's religions.
This idea has many implications, of course. For one, every entity has a potential role to play in the development of our species and the entire world. We have no way of knowing what their significance will ultimately be. So they all deserve a certain degree of respect, don't they? From an occult point of view, it implies that every god and spirit imagined by mankind has real power, because they have shaped entire cultures. The fact that they may be merely concepts in our minds doesn't change that fact.