Those cliches are all very romantic, but your question, "What is the soul?", is a religious question. The "soul" is a religious or spiritual entity. So steering a discussion of "the soul" away from religion leaves nothing to discuss.

I don't believe in the soul. I believe that what you probably think of as the soul (the thing which allows one to think consciously) is part of the brain, and the brain is a part of the flesh. Thus the "soul" is not contained by the flesh; it is the flesh.