Balance

This is just what it says it is. You're looking for things to "add up" in an artwork, for equal amounts of yin and yang, etc. Think in terms of equilibrium. Look for a center point or axis. And think of a seesaw. Part of the beauty of art is you can see the math behind it, if it follows convention. So, a small figure far from the axis would balance out a large figure close to the axis--just as a child at the end of a see saw would balance out an adult near the fulcrum. Only, in art, you must balance more than physical weight or size. For example, you must balance color and "depth." And you deal with balance of abstract to non-abstract. Bear in mind, balance is not always the goal of an artwork. Sometimes, imbalance is the goal, because it highlights some theme or message by increasing its "weight" or importance.