“I have hardly begun to think of the Unity before the Trinity bathes me in its splendour: I have hardly begun to think of the Trinity before the Unity seizes hold of me again.
When one of the Three presents himself to me, I think it is the whole, so full to overflowing is my vision, so far beyond me does he reach. There is no room left in my mind, it is too limited to understand even one. When I combine the Three in one single thought, I see only one great flame without being able to subdivide or analyse the single light.” Gregory Nazianzen Or. 49 on Baptism
Fr. Eric’s Trinity Sunday homily expresses Gregory’s disposition. He introduces two terms that sparkle with meaning: perichoresis and circumincession. Staying grounded Fr. Eric is sublime.
If you still want more, try John of the Cross’ poetic description using three streams of a river as metaphor: