The idea of polar opposites for everything: male and female; night and day; good and evil; and pleasure and pain. Our lives are essentially just a hybrid of opposites, where we struggle to maintain an equivalent balance between the two forces. At times we find ourselves perhaps faltering towards one side too much, where we quickly try to rebalance the forces within us. Interestingly enough, most of life as we know it is dependent on the pain and pleasure concept, where the pain of one action can actually increase the pleasure of the resulting reaction.