Envious

What causes men to become envious of each other I will never know. We are all blessed with what it is ment for us to have. To be envious means ( in my eyes) that your not grateful for what you have been blessed with. I think that at some point in our lives we are all guilty of this. Could it be human nature that drives us to wanting more or "better" then what we have? What drives a man to be envious of anothers worldly possessions? In the end we all have leave it behind.