A Thanksgiving Post
We must posit the existence of incorporeal creatures; because what God chiefly intended in making things was the good that consists in the assimilation to God. But the perfect assimilation of an effect to a cause happens when the effect imitates the cause in the same way that the cause produced the effect, just as heat makes heat. And God made all things by intellect and will.
…The ancients, ignoring the power of what can be known, and not distinguishing between sense and intellect, thought nothing existed in the world except what could be apprehended by sense and imagination…
S. Theo. Q 50 a.1.
What assimilation is:
“To assimilate” someone means to draw them into a shared life. We assimilate immigrants into American culture, for example, when we make them Americans more or less like everyone else. St. Thomas’ proof here begins with the proposition that God intended chiefly that his creation should be assimilated to his life. What does this mean?
Why assimilation was intended in creation
For God to create meant that he wanted some assimilation to himself. Every act of making means that the thing you make has its existence from you, and it cannot exist or be understood apart from you. To exist as an artifact is to exist because of the mind of an artisan. There would be no “Starry Night” without Van Gogh, and the very painting owes its existence to him (so much so that we can refer to the painting as “a Van Gogh”). Every artifact is assimilated to its artisan from the moment of its existence, for its very existence is tied to its sharing in the life of the artisan.
Why assimilation was intended chiefly
Though every making involves some making of a thing that shares in the life of the maker, this is not always the chief thing that the artist intends to do. Those who found states or write books, if they do it well, are not primarily interested in making something that is assimilated to their own life (though this surely happens) but rather in making something that confers on others a good that is higher than themselves. But with God there is no such higher good. All other goods that God could give are subordinate and dependent on the good of assimilation to himself- i.e. that good that comes from a sharing in his own life.
What perfect assimilation is
Assimilation means to cause something to have a shared or common existence. But not everything is equally capable of sharing in a common existence. Van Gogh’s paintings knew nothing about Van Gogh, or about anything else. They could not praise him or even like him. There is an impenetrable wall between our minds and our artifacts at least in this respect- our minds are immaterial and all that necessarily relates to them are not. Our mind as such exists in an entirely different world from the things it creates: inasmuch as it is immaterial, it is measured by eternity; but our artifacts are corporeal, and are measured by time. To perfectly assimilate would mean, for anything making with a mind, to overcome the gulf between the eternal and the temporal, to make another immaterial thing.
Why perfect assimilation was intended by God
The “why” in this question is a why of choice, and not of necessity. There is the further difference that the “why” of our own choices is not precisely the same as the why of the divine choice. In our own choices, the why relates to some good that is separate from ourselves in its existence, for by our choice we are moved by some object, but God is never moved by some good that is extraneous to himself, though he move by choice. When speaking of the divine choices, we can point out why they were fitting, though.
One reason that it was fitting to create a being capable of assimilation by mind was that if this did not happen, then creation would manifest in one sense no greater power than we have ourselves. We can create things that cannot overcome the gulf between time and eternity, and it was only fitting that we expect a higher artisan to do more than this. If God did not make eternal things, it would be something like Michelangelo contenting himself with drawing stick figures. We expect greater artists to make greater works.