Video from The Thomistic Institute
"The Holy Trinity is a mystery in the strict sense—is the mystery of God in Himself. Our knowledge of this mystery 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. 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. The Persons of the Trinity (Aquinas 101) - Fr. Dominic Legge, O.P." from the video introduction.