A basic principle found throughout nature is this: Tension seeks resolution. From the spiderweb to the human body, from the formation of the galaxies to the shifts of continents, from the swing of pendulums to the movement of wind-up toys, tension-resolution systems are in play.
"I call the relationship between the vision and current reality structural tension. During the creative process, you have an eye on where you want to go, and you also have an eye on where you currently are.
There will always be structural tension in the beginning of the creative process, for there will always be a discrepancy between what you want and what you have. Why? Because creators bring into being creations that do not yet exist. Structural tension is a fundamental principle in the creative process. In fact, part of your job as a creator is to form this tension."
From Creating by Robert Fritz