The Holy Trinity is the mystery of God in himself.
It's a mystery in the strict sense.
It can't be proved by rational arguments, and it depends exclusively on God's revelation
and above all, on the Incarnation of the Son, his life in the flesh, and the sending of the
Holy Spirit.
Who are the divine persons?
How can we know them?
In a sense, every Christian already knows something of this mystery.
At every Sunday mass, we profess that we believe in the Holy Trinity, one God who is Father,
Son, and Holy Spirit, and every Christian is baptized in the name of the triune God.
Every mass begins in the name of the Father and of the Son and of the Holy Spirit.
So believing in the Trinity is the very substance of being a Christian, consecrated by baptism
in this holy and mysterious name.
St Thomas Aquinas recommends that starting from this foundational knowledge given to
us by the Christian faith, we push our minds to probe more deeply into this highest mystery.
While keeping in mind our limits, our minds will not be able to investigate
it fully and in this life will never adequately grasp it.
Still, we hope to grasp it one day in heaven when we will see God directly in the beatific vision.
In this life though, inquiring into the names and identities of the divine persons
elevates our spirits so that our minds get some glimpse of the highest truth.
And Aquinas thinks this is very worthwhile, because the ability to grasp something of
the highest things, if only with a feeble and limited understanding, gives us the greatest
joy.
To make this ascent with our minds requires the purification of our images and concepts
so that they can apply truthfully to God.
That's a challenge for us because we often understand things by using analogies to other
things that we know, and from those things we construct images in our minds.
But when we're speaking about the divine persons, nothing in this world will be fully adequate
to the divine reality, and no image will be able to represent God without introducing
some distortion.
The best place to turn for coming to know the names, for grasping something
of the identity of the divine persons, is Sacred Scripture, and that's precisely what St. Thomas
does.
In doing this, he notes that we find two kinds of names in Scripture.
Some names are proper to a single divine person, and they designate what is really distinct
about that person.
They are proper names.
But we also find in Scripture other names and titles that--technically speaking--could
belong to any of the three divine persons, although they're especially applied to or
appropriated to one of them.
So in the Gospels we often hear Jesus referring to his Father, and he also tells us that he
is the of the Father and likewise that he will send us the Paraclete, the Holy Spirit
from the Father.
Now all of these are proper names.
But we read elsewhere in Scripture other names and titles for example, that the Father is
almighty or omnipotent.
This title is appropriated to the Father, because in truth all three divine
persons are almighty.
Let's say a further word about this proper name, Father.
In one sense, the name Father can apply to God simply speaking, in so far as God is the
source of creation and exercises a kind of providential care and love for creation.
There's an analogy to human fatherhood here, because human fathers are a certain source
for their children and also care for their families.
When we say this, it's important also to remember that there are distortions that can creep
into our human experience of family life and of fatherhood and to remember that God is
not male or female, but rather is the source of all, and this is what the word father is
pointing to when we speak about God in general.
In another sense, the word Father designates the first person of the Holy Trinity, the
one who is a principle without a principle, the one from whom proceeds the Son and the
Holy Spirit, and we principally understand him in relation to his Son.
The Son has three proper names revealed in Scripture:
Son, Word, and Image.
The Gospel of John uses two names in a single sentence.
"The Word became flesh and dwelt among us, full of grace and truth.
We have beheld his glory, glory as of the only Son from the Father."
And we learn in Colossians chapter one, "He is the image of the invisible God."
How to understand this.
Building on an insight of St. Augustine, Aquinas thinks the most fundamental name here is "word,"
and from there we will be able to understand the names of Son and Image.
Try this thought experiment.
Think of yourself.
Imagine being able to conceive in your mind a perfect image of your very self.
An image that perfectly captures who you are, everything about yourself.
For us, forming a perfect idea of ourselves is very difficult.
Our minds are limited, and we don't perfectly understand ourselves.
We're creatures in time.
We have bodies; we change; we have a past and a future, and much about us remains obscure
and unknown to us.
But this thought experiment shows us at least this much.
As you understand yourself, there is something in your mind, a kind of idea or image or mental
word that is both from you and remains in you,
distinct from you who are thinking it, but that also corresponds in some way to who you
are.
It's the fruit of your act of understanding yourself.
And in a very limited and partial way you can be in your mind without producing another
you.
Now, God's intellect is infinitely superior to ours in one eternal now, he understands
himself in an infinitely perfect way.
He conceives an image of himself that is a single divine word that expresses himself
with absolute perfection, and this is the Son, the image of the invisible God.
Since God is a pure spirit without a body, his spiritual and immaterial Word
is perfectly identical with the one who speaks it in eternity, in absolutely every way except
for one.
The divine word is God from God.
He is from the Father.
This is the Father's eternal generation or begetting of the divine Son.
And as God conceives his Word by one perfect act of self-understanding, he likewise loves
what he understands as perfectly and infinitely good, and so from the Father and the Son proceeds
a third person, the Holy Spirit, who is divine love in person.
Or to put it another way along with the Father, the Father's word breathes forth love in the
person of the Holy Spirit.
This proper name Word then designates that the second person of the Trinity proceeds
by way of intellect.
Finally, the third person of the Trinity is known by three proper names, Holy
Spirit, Love, and Gift.
The most prominent of these names is Holy Spirit.
Now Aquinas thinks that even though the words "Holy" and "Spirit" taken separately could
refer to God as a whole, taken together, they form a single proper name that refers to the
Holy Spirit's unique way of proceeding.
From the Father and the Son by way of breathing forth or spiration, the Father
and Son breathe forth
the third person who is thus rightly named the Holy Spirit.
Love is also a proper name for the Holy Spirit.
He proceeds by way of love as the mutual love of the Father and the Son.
From this proper name of Love, we see why a third name used for the Holy Spirit by Jesus
in John's gospel, that he is Gift, also counts as a proper name, because love is the reason
for a truly gratuitous gift.
And this proper name of gift points out to us the Spirit's aptitude--his readiness--to
be given to human beings in the invisible mission of grace.
These names of the Holy Trinity give us a glimpse into the heart of the mystery of God
in himself.
And even though we don't fully grasp what they signify in God, Aquinas thinks that we
should give thanks to God for the great privilege of knowing him by name.
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