There is a natural ordering of intellectual abilities, in us and in angels.
1 Since certain intellectual creatures are higher than others, as is clear from the foregoing, the lower ones of an intellectual nature must be governed by the higher ones.
2 Again, more universal powers are able to move particular powers, as we said. But the higher intellectual natures have more universal forms, as was shown above. Therefore, they are capable of ruling the lower intellectual natures.
Notes This occurs in humans, too. But it is nothing to boast of. The more you are given, the greater your responsibility, and the greater your culpability when you fail.
3 Besides, an intellectual potency that is nearer to the principle is always capable of ruling an intellectual power that is more removed from the principle. This is evident in both speculative and active sciences; for a speculative science which derives its principles of demonstration from another science is said to be subalternated to that other; and an active science which is nearer the end, which is the principle in matters of operation, is architectonic in regard to a more distant one. Therefore, since some intellectual substances are nearer the first principle, namely God, as was shown in Book Two , they will be capable of ruling others.
4 Moreover, superior intellectual substances receive the influence of divine wisdom into themselves more perfectly, because each being receives something according to the being’s own mode. Now, all things are governed by divine wisdom. And so, things that participate more in divine wisdom must be capable of governing those that participate less. Therefore, the lower intellectual substances are governed by the higher ones.
5 Thus, the higher spirits are also called angels, because they direct the lower spirits, as it were, by bringing messages to them; in fact, angels are spoken of as messengers. And they are also called ministers, because they carry out by their operation the order of divine providence even in the area of bodily things. Indeed, a minister is “like a living instrument,” according to the Philosopher [Politics I, 4: 1253b 29]. So this is what is said in the Psalm (103:4): “You make your angels spirits, and your ministers a burning fire.”