PersEternity

Definition: This is an analogy that Plato uses to distinguish among different forms of knowledge and truth. Plato's basic division is between what is visible and what is intelligible (i.e., knowable, but not seen), with the visible portion smaller than the intelligible portion. The visible portion of knowledge is further divided. At the lowest end of the visible are mere images of objects, but above this is understanding of visible objects. Above this in turn is knowledge of abstract mathematical principles, then knowledge of forms. At this highest level is knowledge of good as a form and knowledge of the forms and how they are organized. Understanding the analogy of the divided line requires an understanding of Plato's theory of forms and his allegory of the cave.

Background: As a Pythagorean theorist, Plato makes a good deal of the idea that the empirical world is but a pale reflection of the true world of enduring and ideal forms. The analogy of the divided line is essentially an elaboration of the distinction between the vulgar visible world and the ideal world that is not directly seen. In the analogy of the divided line Plato further subdivided the visible and invisible worlds further.