Analogy of the divided line refers to Plato's illustration of his contention that there is a hierarchy of understanding. The lowest type of understanding is based on images of empirical objects. Next highest is an understanding of empirical objects themselves, which results only in opinion. Next is an understanding of abstract mathematical principles. Then comes an understanding of the forms. The highest understanding (true knowledge) is an understanding of the form of the good that includes a knowledge of all forms and their organization.