There seems to be several possibilities on which to choose from in regards to what call the existence of the soul. Some might suggest that there is no such thing, that perhaps what we call the intellect is tied strictly to our chemical composition. While there may be evidences in brain surgery to suggest how we respond to stimulation, there is something even greater and more complex... a miracle as it were... that our souls are much greater than just a chemical composition and process. The miracle of life has never been able to be reproduce from inanimate objects. But our capacity as man is much greater than any other animal when we become adults, and this capacity is to reason and with this reason to create complex objects for use, and to also give in-depth meaning to our universe and communicate these ideas. A whale may be more intelligent to man, but I do not think they are able to think up even the error that matter is of four substance air, wind, water, and fire much less that there are numerous atoms that make up our periodic table of elements.
So establishing ourselves from amongst the other animals, the greatest on our planet, I wish to jump to a Christian perception. An ****ogy that seems useful is the Temple which is composited of the outer court, inner court, and Holy of Holies; hence is drawn the physical body, the soul, and then the spirit. Some may interchange spirit with soul and combine them, which is alright in my book, so long as what I am suggesting by the Holy of Holies to be that place where either God resides in the center or that center is filled with one self or another spiritual deity. Hence, if we allude to even other cultures that understand such a thing as demon possession, that center is filled with something other than the person we know.
I am sure there is much in way of divergent ideas on the soul. For some, the soul is eternal that has no beginning nor end. At any rate, I just thought an ontological think-speak on the subject would be refreshing. I suggest its importance is far reaching. Depending on how one views the existence of the soul will change the importance of eternal consequence in recognizing a universal code of ethics and morality. As such it also ties to our ideas of the afterlife and what we are trying to attain, paradise, Nirvana, heaven, (perhaps even hell, if Milton's "Paradise Lost" comes to mind about it better to reign in hell than serve in heaven). So there is relevance to the subject.