1. The better a thing is, the higher place does it hold in the intention of the agent who produces it. But the best thing in creation is the perfection of the universe, which consists in the orderly variety of things:* for in all things the perfection of the whole is preferable to the perfection of parts and details. Therefore the diversity of creatures does not arise from diversity of merits, but was primarily intended by the prime agent.
2. If all rational creatures were created equal from the beginning, we should have to allow that they do not depend for their activity one on another. What arises by the concurrence of divers causes working independently of one another is matter of chance; and thus the diversity and order of creation comes by chance, which is impossible.*
12. Since a spiritual creature, or angel, does not deserve to be degraded except for sin, -- and it is degraded from its high, invisible estate, by being united with a visible body, -- it seems that visible bodies have been added to these spiritual creatures because of sin; which comes near to the error of the Manicheans, who laid it down that the visible creation proceeded from an evil principle. Origen seems not to have given sufficient weight to the consideration that, when we give, not in discharge of any debt, but out of liberality, it is not contrary to justice if we give in unequal measure: but God brought things into being under no debt, but of sheer liberality (Chap. XXVIII): therefore the variety of creatures does not presuppose variety of merits.
2.41 : That the Variety of Creatures does not arise from any Contrariety of Prime Agents
2.45 : The real Prime Cause of the Variety of Creatures