Formal opposition can be established between type and image. The more opposition and congruence created between the two creates a richer relationship and creates more interest. If the two are too much alike interest is lost because there is no contrast. Hierarchy can be destroyed when the two are too similar. You want the contrast to make the opposing characteristics stand out. The seesaw method is a kind of equilibrium. This is when you establish a balance between the relationships of congruence and opposition. You always want to keep establishing unity in mind.