That there is no light without the dark. Everything has its other side. I am basically a good person, but I have the potential to be violent or evil. This differs from how I interpreted former president George Bush's talking about the "Evildoers." It seemed they were "they," and not the potential to be he.
If we don't recognize that we have shadow sides, which are unknown or unlived parts of ourselves, those unknown parts will come out in ways that are out of our control and that we may not admit to. (An aside, our shadow side may be our magnificence if we haven't claimed that part of ourselves.) We want to give ourselves choices in how we will behave, rather than just reacting.
So I thank that duck hunter for reminding me of the wholeness of life. There is good and evil, greatness and mediocrity, nonviolence and violence, joy and sadness, peace and war, light and dark.