What is a soul?

I am reading The Holy Longing again. I first read it as part of a class but now am reading it with a group of women I meet with each week. The first chapter discusses the two functions of the soul. It is both the life force within us and that which holds us together. It is the very essence of who we are as individuals. It contains our fire and helps us make sense of what we are about. It is no wonder that when my soul is not fed, I get restless and unfocused, unsure and discouraged; my fire dies. I need to nourish my soul by doing what brings me joy and trying to rid myself of whatever steals my joy. All of us need to do this, because our life is given to us one time only. What nourishes your soul?