They greatly affect one's interactions with reality. Science might claim that these two levels are all that exists, although the second layer of reality, the mind, is a little harder to explain in terms of matter and energy. Soul There is more to a human than just the thought patterns and bodily functions and actions. There is an awareness of oneself. But, more importantly, to know that you are.
Humans can look at their lives, and other's lives, and plan courses of action.
They are not necessarily bound to a stimulus producing a set response. Humans can observe a situation and weigh out various courses of action. They can set goals and push themselves over obstacles to achieve those goals, even if they are abstract and intangible. This Observer, or soul is the third level of consciousness. It is the part of us that we think of as the real us inside.