Why is there darkness in humanity?

              As every human knows, there is darkness in humanity. No matter how much we try to abolish it, or how much we try to convert evil forces into good ones, darkness will always exist. Darkness is in the world for a reason: so good can exist. Honourable deeds can only be recognized if we have experienced bad ones. For instance, one cannot say they have had a good day until they have had a bad one. If every day was wonderful, it wouldn't feel wonderful anymore. It would feel neutral and dull, since there would be nothing to compare it to. Pleasant feelings can only be felt if we have felt the darkness of sadness. Basically without darkness we would not have the contrast necessary to recognize good in our world. Thus, although the human race regularly despises darkness in humanity, we should remember how essential it is to our lives.