Here's a shot at a paraphrase of the part that stuck with me, which may or may not be anything close to accurate, given that I've been even more distracted than usual these days and that I don't always catch everything when listening in Italian. If my confrere should ever see this and feel that I have I misinterpreted him in any way, he may correct me in any way he sees fit and I will happily remove the post.
What hooked me was the comment that the Trinity is a doctrine against those who only know how to talk about themselves. Intriguing, I thought. The mysteries of the incarnation, passion, death, and resurrection of the Lord--in which the Blessed Trinity is definitively revealed to us--show us that God, precisely in being properly himself, comes to include us in his divine life. In other words, in order for God to 'be himself' [as our kindergarten teachers advised us all to do] he has to draw us into himself, sharing with us the blessedness that he is.
From the other side, we then learn that we only come to know our true selves when we discover ourselves in God and in giving ourselves to our neighbor, imitating the original blessedness that is the Blessed Trinity.
God isn't like a person who only talks about himself. The Holy Spirit conceives his Word among us that we may find ourselves and our voices in him and with each other.
Simple. But all the doctrine is there. And I mean 'doctrine' in the gentlest sense of that which should help us be docile, ready to be taught and led into blessedness.
It reminds me of the time I realized that I could no longer tell my own so-called 'conversion story' without first telling the story of Jesus Christ. At that moment I had new courage to call myself a 'Christ-ian.' Not that I've always had that courage since, but graces lost are just as valuable; after all grace is God and God is outside of history, personal and otherwise.
It also reminds of St. Francis and how, when he goes to tell his own conversion story, the first character we meet isn't Francis at all but the Lord: The Lord gave me, Brother Francis, thus to begin to do penance in this way... The 'main character' in Francis's 'conversion story' isn't Francis, but Jesus Christ.