The concepts of “fire” and “water” do not refer to actual fire and water. They are symbolic of the deeper sides of our nature.
The fervor and impetuosity of people is passionate and volatile and so it is referred to as fire. The other side of people’s character, the calm, centered, more contained and wise side is steady and careful. It has a more settled quality, a “softness”, a “flexibility” which contrasts with the fiery and volatile side, and so it is referred to as water.
Using the more contained and settled “water” side is using thoughtfulness, logic, and control to nurture and guide our more impulsive and wild side. Using the other side of our disposition, the excitable and temperamental “fire” nature, to complete and balance the often too staid and overly controlling “water” nature is allowing that side of our character expression. By finding a balance between these two sides of our makeup we become more complete and whole.