But just because we can't understand the Trinity completely doesn't mean we can't understand it at all.
The great apologist Frank Sheed used to give a very interesting explanation of the Most Holy Trinity.
He started by thinking about our own human nature.
Each one of us exists, but since we are spiritual, we also have an idea of ourselves.
We can think about ourselves, reflect on ourselves, know ourselves.
This is why human beings are the only animals on earth who write diaries.
That's similar to what happens in the relationship between God the Father and God the Son.
God the Father is spiritual, able to know himself. He has an idea of himself.
But, since his knowledge is limitless, unlike ours, that idea of himself is perfect, perfectly complete.
But to be perfect, it has to share in God's own existence; it has to actually be a divine person.
And so, God the Father, from all eternity, knowing himself, engenders the Son, the perfect image of the Father.
And then, of course, since both the Father and the Son are infinitely good and beautiful, as soon as they know each other, they also love each other.
Even we, when we think about ourselves, love ourselves.
We want the best for ourselves. We are glad that we exist.
But God's love, like his knowledge, is unlimited, and so it too has to be so intense and so full that it shares fully in the divine existence; it is a divine person - the Holy Spirit.
This is the mystery we profess each week when we affirm our belief in the Son of God, who is "one in being with the Father, God from God, light from light" and in the Holy Spirit, who "with the Father and the Son is worshipped and glorified."
In the Christ who we share, Fr. John J Gordon, O.M.I