Is Evil an unessesary stain on history?

"On the way to good and evil" was a bit over my head, but a few things did stand out to me. The author states that "The stain of human evil covers the earth and seeps into all man's achievements in art, science, and in the institutions of society." This seems to be completely true! I do a lot of theater and I do not know of any play that does not have any evil in it. For example, the play Romeo and Juliet by William Shakespeare has evil in it, the animosity between the two houses is the main evil that we are aware of in the story. There is also killing of people's friends and death of beloved characters, these also represent evil. This story would not be as compelling if there were no forces of evil in the story. Would anyone watch a play about two people who fall in love, have no relationship issues, their families get along, they get married and everyone from both weddings attend the wedding in a joyous celebration? Maybe, but it would not be as famous as Shakespeare's Romeo and Juliet.

Socrates told us that "We may understand intellectually what is good, while yet desiring and choosing to do something entirely different-and vica versa." This is pretty much the main issue that many of us deal with every minute of everyday. We know we should be doing homework, but instead we watch that one episode of Lost that we have been meaning to watch off of our Tevo. We are happier watching Lost, but we know we should be doing that blog for our Ethics class! We all desire things that we shouldn't have and most times (hopefully) we don't give into these desires. I am allergic to wheat, but I desire bread, yet I do not eat the bread, but I still desire it. Why does my mind work against itself by desiring things that I shouldn't want or have?