St Augustine's theory of illumination consists of different degrees of reality and being. He views the world as being hierarchically arranged. St Augustine maintains that nothing is completely real with the exception of God. God is the intelligible light beyond all light and the primitive rich source of brightness that extends to all intelligence. There are different levels of reality. Hence the hierarchy of value becomes also a hierarchy of reality, so that it makes sense to speak in degrees of being. (Anthony Kenny, Western Philosophy) The hierarchy is arranged as follows; God is at the top, while physical objects are considered being nearly unreal, and human souls are somewhere in between. The souls of good people are higher than those of the evil ones. Good angels are below God but above the souls of good people. Fallen angels are somewhere between the souls of wicked people and physical objects.
It is just an arrangement of how Augustine's sees their value.
As our eyes have need of the light of the sun in order to see sensible objects, so does our mind need the light of God to know the world of understandable beings? Everlasting truths, ideas, species, formal principles are imparted to our intelligence by Wisdom, the World of God. ( Kenneth Young, Stanford University)
St Augustine maintains that if degrees of goodness are identified with degrees of being, there can be nothing purely evil. In fact it is St Augustine's position that an absence of good doesn't mean that there is evil. Therefore there is no evil in the hierarchy. St Augustine believes that evil is merely a form of injustice. There is no such thing as evil; he regards evil as being disorder. In retrospect St Augustine believes that something with a low degree of goodness is...