I am an ardent believer in being exposed to Trinitarian grammar as much as possible. The mysterium Trinitatis is a reality that all Christians, at all times, in all places ought to be getting lost in over and over again. I find great joy, and a peace that surpasses all understanding as I contemplate the great mystery of the triune reality; but I don’t do see blindly. To think God as triune is to think concretely about the divine life as that has been Self-revealed and exegeted for us in God’s givenness for us, with us, and in us, by the Holy Spirit in Jesus Christ. St. Augustine captures the sense of what I’m after this way:

Should I even ask, O Lord? Should I even ask? You have spoken, and you have acted, and you have called us to believe. You have taught us that we walk by faith and not by sight, by trust in your good promises of goodness, and not by understanding. It is enough that you know the nature of things. Should I ask?

If I ask, will I receive an answer? You are beyond all my thoughts, greater than all that I can say, incomprehensible in your eternal communion as Father, Son, and Holy Spirit. You cannot be encompassed with any concept, bounded by anything greater than yourself, since you are greater than all. All my efforts to encompass you are acts of idolatry and not true worship. And you made all things and all things shine with the bright radiance of your glory. Your world seems as incomprehensible as you yourself.[1]

With this sense of awe about who God is, as that is set before us by Augustine, let’s turn to Gregory Nazianzus to get his eloquent and rather to the point thinking on who God is as the Triune reality:

I set before you the One Deity and Power, Found in the Three-in-Unity, Embracing the Three one by one, equal in essence and nature, Neither increased not decreased by ideas of greater or less; In every way equal, in every way the same, Just as the loveliness and hugeness of the heavens are one: The infinite oneness of Three Infinite Ones, Each of whom is God when seen individually in Himself. As the Father is God, so is the Son, And as the Son is God, so is the Holy Spirit; And the Three are likewise One God when seen together. Each is God because they are of the same essence, And they are One God because of the single principle of Deity. The very instant I conceive of the One, I am enlightened by the brightness of the Three; The very instant I differentiate them, I am carried straight back to the One. When I regard any One of the Three, I think of Him as the Whole; My sight is filled to the brim, And the greater part of what I am thinking of eludes me! I cannot grasp the greatness of One of the Three So as to reckon a greater greatness to the Others. And when I see the Three together, I see only one torch, And I cannot divide or share out the Undivided Light.[2]

³³ Oh, the depth of the riches and wisdom and knowledge of God! How unsearchable are his judgments and how unfathomable his ways!

³⁴ For who has known the mind of the Lord,
or who has been his counselor?
³⁵ Or who has first given to God,
that God^] needs to repay him?

³⁶ For from him and through him and to him are all things. To him be glory forever! Amen.[3]

[1] Augustine cited by Peter J. Leithart, Athanasius, xv-xvi.

[2] Gregory Nazianzus cited in, The Early Church Fathers, edited by Nick Needham (Scotland, UK: Christian Focus Publications, 2017), March 7^th entry.

[3] The Apostle Paul inspired by the Holy Spirit, Romans 11:33-36, NET Bible.