Today's readings recount the unforgettable events of Pentecost. Language is our primary mode of communication. How wonderful, therefore, that the principle gift of the Holy Spirit at Pentecost is tongues - speech, language - enabling the first disciples to establish heart-to-heart communication with the peoples of the world. The Holy Spirit himself is nothing but communication for the Spirit is nothing other than the love that connects the Father and the Son. When the disciples, filled with Holy Spirit, go out to communicate on Pentecost, they effectively unite the world by gathering what sin has scattered.
Bishop Barron’s Sunday Sermons - Catholic Preaching and Homilies