Actually, I wrote this not long ago. In fact it was written last year. But, I think it is appropriate to post it again. After all, our Holy Catholic Church celebrates this day annually, so, in a sense, this post will never be outdated. God bless you on this great feast day!
I can’t think of any doctrine more basic to Christianity than that of the Trinity. The Catechism of the Catholic Church defines the Trinity in this way:
The mystery of one God in three Persons: Father, Son, and Holy Spirit. The revealed truth of the Holy Trinity is at the very root of the Church’s living faith as expressed in the Creed. The mystery of the Trinity in itself is inaccessible to the human mind and is the object of faith only because it was revealed by Jesus Christ, the divine Son of the Eternal Father.
In YOUCAT, the Youth Catechism of the Catholic Church, there is this distinction:
God is only one, but he exists in three persons. The fact that in English we have two terms, the Triune God and the Trinity for the same reality (one emphasizes God’s unity, and the other the distinction of persons in him) is an indication of the unfathomable mystery of the Trinity.
St Augustine says, “Wherever there is love, there is a trinity: a lover, a beloved, and a fountain of love.”
From St. Gregory Nazianzen:
No sooner do I conceive of the One than I am illumined by the splendor of the Three; no sooner do I distinguish them than I am carried back to the One. . . When I contemplate the Three together, I see but one torch, and cannot divide or measure out the undivided light.
Paraphrased remark attributed to St. Bonaventure: “The three persons of the Trinity are described as being in an eternal dance of love.”
Here is a beautiful, inspiring Celtic prayer to the Holy Trinity, which I found in The Essential Catholic Prayer Book.
I am bending my knee in the eye of the Father who created me,
In the eye of the Son who purchased me,
In the eye of the Spirit who cleansed me,
In friendship and affection.
Through your own Anointed One, O God,
Bestow upon us fulfillment of our need,
Love toward God,
The affection of God,
The smile of God,
The wisdom of God,
The grace of God,
The fear of God,
And the will of God,
To do in the world of the Three,
As angels and saints
Do in Heaven;
Each shade and light,
Each day and night,
Each time in kindness,
Give us your spirit.
Other sources of reflection about our loving, but mysterious, Triune God:
This link is a rich resource to “15 Things about the Holy Trinity Today” by Kathryn Jean Lopez.
This link will take you to the essay I wrote in my parish bulletin for today. In it is an explanation of the triquetra or Irish knot. You will have to find the bulletin for 5/31/15. It’s tricky: go to the left hand side bar and scroll down to “Go to Bulletin.” They are arranged by date, newest first.