Frank Sheed explains the Trinity
The following is an excerpt from Frank Sheed’s Theology for Beginners (pages 28-29):
I once heard a theologian (not of our faith) say, when someone asked him about the Trinity: “I am not interested in the arithmetical aspect of the Deity”; even Catholics sometimes appear to think that we have here a mathematical contradiction, as if we were saying, “Three equals one.” We are not, of course. We are saying: “Three persons in one nature.” The trouble is that, if we attach no meaning to the words person and nature, they tend to drop out; so we are left with the two numbers, as though they represented the supreme truth about God.
The first stages of our investigation into person and nature are simple enough. We use the phrase “my nature,” which means that there is a person, “I,” who possesses a nature. The person could not exist without the nature, but some distinction there seems to be - the person possesses the nature, not vice versa. We say, “my nature,” not “nature’s me.”
Further, we see that person and nature answer two difference questions. If we are aware (in a bad light, say) that there is something in the room, we ask, “What is it?” If we can see that it is a human being, but cannot distinguish the features, we ask, “Who is it?” “What” asks about nature, “who” asks about the person.
There is another distinction which calls for no special philosophical training to see. My nature decides what I can do. I can raise my hand, for instance, because that action goes with human nature; I can eat, laugh, sleep, think, because each of these actions goes with human nature. I cannot lay an egg, because that goes with bird nature; if I bite a man, I do not poison him, because that goes with snake nature; I cannot live underwater, because that goes with fish nature. But though it is my n ature which decides what actions are possible to me, I do them, I the person; nature is the source of our operations, person does them.
Applying this beginning of light to the being of God, we can see that there is but one divine nature, one answer to the question “What is God?”, one source of the divine operations. But there are three who totally possess that one nature. To the question “Who are you?” each of the three could give his own answer, Father or Son or Spirit. But to the question “What are you?” each could but answer “God,” because each totally possesses the one same divine nature, and nature decides what a being is.
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