Today’s Aquinas: How Come I’m Not a Trinity?

We’re blogging through St. Thomas Aquinas’ Compendium Theologiae, sometimes called his Shorter Summa. Find the previous posts here.

Having consider each person of the revealed Trinity in turn, Thomas now turns his attention to the Trinity as a whole.  The following is an admirably clear and concise summary of the last twenty or so chapters:

We must conclude from all we have said that in the Godhead there is something threefold which is not opposed to the unity and simplicity of the divine essence. We must acknowledge that God is, as existing in His nature, and that He is known and loved by Himself.

While God is simple and cannot be separated into parts, yet there is a “threeness” within God.  How can there be three and yet still one?  Thomas will address this question in detail over the next couple of chapters.  Here, he has a different target in view.  I as a human being am known and loved by myself; and yet I remain one.  Me, myself, and I all refer to the same single person.  Why is it different with God?

Thomas explains,

But this occurs otherwise in God than in us. Man, to be sure, is a substance in his nature; but his actions of knowing and loving are not his substance. Considered in his nature, man is indeed a subsisting thing; as he exists in his mind, however, he is not a subsisting thing, but a certain representation of a subsisting thing; and similarly with regard to his existence in himself as beloved in lover.

By subsisting thing Thomas means an object rather than some aspect or feature or detail of an object.  The quality of ripeness exists in a ripe apple but it doesn’t exist by itself; take the apple away and the ripeness goes with it.  The apple subsists, but the ripeness doesn’t.

My idea of myself is more like the ripeness than the apple. When I think of myself, there is certainly an idea of myself in my head.  But how far that idea falls short of the fullness of my being!  I know that I am made of a myriad of cells, but I can’t count them; I can’t even number the hairs on my head.  I have a notion of my own beliefs and behaviors, and yet there are things about me that are obvious to everyone who knows that I’ve never ever suspected.  I have that voice that drives my kids nuts, and I’m seldom aware of using it.  I have an idea of me, but the idea is not me but only an abstraction of me; and it exists only while I’m thinking it.

Thus man may be regarded under three aspects: that is, man existing in his nature, man existing in his intellect, and man existing in his love. Yet these three are not one, for man’s knowing is not his existing, and the same is true of his loving. Only one of these three is a subsisting thing, namely, man existing in his nature.

And so I’m not a trinity, and neither are you.

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photo credit: Public Domain; source Wikimedia Commons