One of the central issues, or indeed the central issue in Plato's philosophy is the question of how to account for the stability and unity of the seemingly unstable and ever changing world.<br/>How could we attain knowledge if there were no stable object? And how could the world be what it is, if it were not grounded on stable principles? It is common knowledge that Plato answers both these questions, an epistemological and an ontological one, by his theory of the Forms.<br/>From an epistemological viewpoint, the Forms constitute the objects of true knowledge. From an ontological point of view, they are the principles that underlie the order of the universe.