To Aquinas’s mind, distinction and hierarchy within creation is a necessary consequence of the Creator-creature distinction, of the distinction and hierarchy, that is, obtaining without creation. He writes:
a thing approaches to God’s likeness the more perfectly as it resembles Him in more things. Now, goodness is in God, and the outpouring of goodness into other things. Hence the creature approaches more perfectly to God’s likeness if it is not only good, but can also act for the good of other things, than if it were good only in itself; that which both shines and casts light is more like the sun than that which only shines. But no creature could act for the benefit of another creature unless plurality and inequality existed in created things. For the agent is distinct from the patient and superior to it. In order that there might be in created things a perfect representation of God, the existence of diverse grades among them was therefore necessary. (SCG 2.45.4)
The good of creation, in other words, is to reflect the divine likeness; God’s own likeness, however, is revealed in his “outpouring of goodness” into those things other than and below himself. This means that the created order, if it is at all to emulate adequately God’s goodness towards creation, must itself consist in a hierarchy of diverse and unequal beings. Only in this way can the divine drama of a higher reality ministering to and bringing to perfection a lower order of being be carried out on a finite scale.
And if so, then a denial of the consequent (hierarchy within creation) for Aquinas would therefore seem to entail a denial of the antecedent–the hierarchy between Creator and creature. An egalitarian ontology of creatures is veritable atheism.