This was a theory I had that although I did not believe in any sort of all supreme higher being, God, Buddha whatever there was something more than this mortal existance. The song suggests there is an energy, intrinsic to life itself that we all share, not just human kind but all living matter and that this energy force is what stokes the engines of that thing we've named "The Soul". Our comprehension, our intepretation of this energy is determined by our biological makeup, the size of our physical mind etc. So being at the top of the evolutionary tree our brains are filled with this energy, this soul force but due to our unique biological makeup this translates into our mind being able to think, to dream, this allows us all the emotions that make up the human species. It suggests the soul is not an individual thing of which we all have our own but more a universal thing of which we all share a part of. Not sure if I believe this nowadays in fact I struggle with the concept of a soul all together.