Equilibrium is the condition of a system in which all competing influences are balanced.
Aesthetic harmony in an image is a form of equilibrium. A simple grid allows for exploration of aesthetic harmony. The points of a grid can vary in structural or chromatic intensity. The particular variations that are harmonious are a proper subset of all possible variations; identified both by what they are and what they are not. They are events. They have duration but they do not endure. Their fleeting existence can only ever be felt.