Aristotelian Philosophy and Understanding the Doctrine of the Trinity

In Aristotelian philosophy, there are a lot of terms thrown around like essence and potentiality, and all sorts of other sorts of terms too, each with its own definition. These terms are sometimes used to clearly define doctrinal points, so for example, the doctrine of the Trinity is often described in philosophical terms by saying that God is three persons in one Being.

Can anyone give me a clear definition of how Aristotelian philosophy uses the terms person and being in this context? I’m guessing the term being is the Greek word οὐσία, but I’m not totally sure on its definition in the philosophical sense, and neither am I very clear on the meaning of the term person.

I’m guessing that the Greek word you are wondering about is " ousia, " which would be equivalent to substance in English or " substantia " in Latin. Substance of course refers to the underlying reality which supports all accidents of a being ( i.e. quantity, color, shape, operations, etc.)

In regard to various philosophical terms which may be used in Catholic Theology you can look them up in the Catholic Encyclopedia at

Also -

Beyond that I would recommend " Aquinas " by Edward Feser

As to the Trinity, see the Catechism of the Catholic Church, paragraphs 232-278

Also: Trinity -

Simply. Catholics believe in One God in which there are three Persons, the Father, the Son and the Holy Spirit. Each Person is the same God, fully, compeletely, having the same Being, Substance, Essence, Nature, etc. The Father eternally begets the Son, and the Holy Spirit eternally proceeds from the Father and the Son. They are known to us by Revelation only, it is a mystery, no human can define accurately and fully much more than this. Other than this we know that each has been revealed as engaging Creation in certain ways. The Father creates, sustains, and directs, the Son saves and justifies, the Holy Spirit spoke through the prophets and continues to guide the Church in all truth necessary and beneficial to salvation and bestows God’s grace through the Sacraments. But in fact, each Person is doing what the other is doing. Again this is a mystery which we cannot understand, so don’t expect an answer attempting to explain much more than I have said. :thumbsup:

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.

Tou can read more at…ts_may2011.asp

I want to propose an analogy to try to stab at that.

I am a computer programmer and I design a game, in it there is a world with laws that govern the interactions of the elements that make up the game.
Then I create characters and give them the chance to interact with their world and reproduce, expand, build, learn etc.

It could be said that I am their “god” since I can modify their world at any time.

Now I want to somehow influence the way the characters behave or act.
I do this by sending out ideas or behavioural concepts to certain specific characters by writing my ideas into their cognitive process, they in turn will influence the population.
This would be akin to the Holy Spirit talking to the profets and through them.

Finally I want to make 1 character that will have a vast impact on the other characters so I infuse him with all my knowledge and morals and all that make me me.

This would be the analogy to Jesus, He is the incarnation on our reality of the Creator God.

They appear to be 3 separate and distinct persons and at the same time are the same essence.
Of course this is but a simplistic explanation and the full mistery will be more fully revealed to us in the next life.

DISCLAIMER: The views and opinions expressed in these forums do not necessarily reflect those of Catholic Answers. For official apologetics resources please visit