This poem is a beautiful expression of the necessity of dichotomy. How would we know what joy is without having known sorrow? How can we distinguish what is true without knowing what is not true (lies)? It's all relative. If all we experienced was so-called good, we would not know it as such because we would not have a point of reference to contrast what it would be like otherwise. Each are two sides of the same coin, without one side, it would be incomplete.
Humans are such beautifully complex yet simple beings. The range of emotions and actions described in the poem encompasses many of the experiences that enrich and challenge us personally as well as when dealing with other people. I think the key to embracing all that is, is acknowledging that each characteristic is not necessarily a reflection of who that person is, but is an outward reflection of his/her experience of life at the time. I believe that we all have the ability to choose who we are going to be from moment to moment, but at the very core each and every one of us is a love being. Therefore when faced with those who are not aligned with the truth, those who are mean, fail, wail, lie, what have you, we must look to the core of who we are, and choose love. Every time.