Moderation is a specific kind of balance. It means recognizing that too much of any good thing is bad.
Many qualities, resources or activities can serve the health and well-being of humans or the web of life we call home. But even a virtue when pursued to excess crowds out other virtues and causes harm. When we practice moderation we seek to find the balance between insufficiency and excess.
The greatest barrier to moderation is our very human tendency to label entities as good or bad in absolute terms rather than weighing them as a part of a greater, complex whole.