In Fully Present, a book by Susan Smalley and Diana Winston on mindfulness and meditation, part of Chapter 6 ("Feeling Bad: Dealing with Negative Emotions") muses on background and balance:
When we are not reacting emotionally, we are in a different physiological state of balance. We all know that balanced feeling—not high or low, not fear or joy, not anger or love, but simply nonreactive. Recognizing your bodily and mental experience in this state of not reacting emotionally is like recognizing the space between words printed on this page, or the background elements of a Picasso painting, or the space within a Frank Lloyd Wright building that makes it an architectural masterpiece.
Mindfulness is a tool for improving your discernment of emotional states (and the bodily changes that accompany them) when they arise. You can become a Sherlock Holmes of your feeling and their associated physiological changes. Through investigation, you can detect them earlier and with finer resolution. Lao-Tzu wrote in the Tao Te Ching, "Deal with a thing while it is still nothing." We all remember times when we could have stopped a situation from evolving into a big mess by catching ourselves—whatever it was we said or did—before the situation escalated. Catching your emotional reactions early, when they are still small, is a way to alter your actions to keep them from fueling difficult situations. Think of a time when you reacted emotionally and that led to big problems; later you probably saw how easy it would have been to just say or do nothing (just "act like a log"). When you pause between emotion and action, your words and actions are less likely to hurt yourself or others because you're able to circumvent or at least lessen your emotional reaction. And because we are only aware of the tip of the iceberg of emotional responses (a huge number of emotional reactions occur unconsciously), the process of discovery is likely to be never-ending. There is always an emotional reaction we are likely to miss.
Or, as good advice that someone like me especially needs to remember: pause before sticking a foot into it!