Athanasius uses the tool of a “divine dilemma” to explain the motive for the Incarnation. A similar tool might be useful to explain what St. Thomas says about the motive for the very creation of human beings.
Teacher: God decided to create the most perfect universe.
response: but He will be no better off with a universe, perfect or not. What motive could he have?
T: He has decided.
r: All right, creation is given. Still, it is impossible to create the most perfect universe. The divine power is infinite, and so given anything, he could always create something better.
T: I don’t mean “the most perfect possible universe” like that. I mean that all possible grades of existence will actually exist. The universe will be a complete whole with nothing left out.
r: That’s a terrible idea! He will have to make things which exist sometimes, and at other times cease to be! There will be death!
T: That belongs to the perfection of the universe. If A comes to be from B, what do you think this means for B?
r: I can accept this at the lower levels of existence, but the very culmination of the physical world is a terrible idea.
T: How so?
r: Because at the highest point of physical creation, there must be some connecting link between the spiritual and material world. This means at some point making spiritual things that exist with an essential relation to matter. What an awful idea! Such a being will be subject to chance, to things he is not ready for, to his own impenetrable ignorance, and to the collective burden of all the mistakes, errors and sins that arose before him! This practically guarantees that the very thing that we put at the perfection of the physical world will be the ugliest thing in it! The whole cosmos will conclude to a monster!
T: that is true, it is a terrible problem. But they are still necessary for the perfection of the universe. If they end up as monsters, who can they blame but themselves? You are arguing against creation as such- but you said this was a given.
(discussion makes an explicit appeal to revelation)
r: Will anything be done to keep the thing at the top of the universe from being a monster?
T: Yes. When this degree of existence arises, God will offer it a supernatural aid, which will enable it to avoid becoming a monster, and attain natural happiness.
r: And what if this aid is rejected?
(Athanasius’s dilemma takes over at this point)