“Every Catholic knows, dearly beloved, that today’s solemnity should be counted among the principal feasts. No one questions the respect due to the day the Spirit made holy by the miraculous gift of Himself. This is the tenth day from the day when the Lord ascended to sit at the right hand of God the Father in heaven. It is the fiftieth day from His resurrection. Pentecost holds great mysteries in itself, mysteries new and old. By them it is clear that grace was foretold through the old law, and the old law was fulfilled through grace. When the Hebrew people were freed from the Egyptians, the law was given on Mount Sinai on the fiftieth day after the sacrifice of the lambs. So, after the suffering of Christ—the true Lamb of God, who was slain—and on the fiftieth day from His resurrection, the Holy Spirit came down upon the apostles and the crowd of believers. The true Christian can easily see how the beginnings of the Old Testament prepared for the beginnings of the Gospel, and that the second covenant was founded by the same Spirit who had set up the first.
The apostles’ story testifies: ‘When the day of Pentecost had come, they were all together in one place. And suddenly a sound came from heaven like the rush of a mighty wind, and it filled all the house where they were sitting. And there appeared to them tongues as of fire, distributed and resting on each one of them. And they were all filled with the Holy Spirit and began to speak in other tongues, as the Spirit gave them utterance’ (Acts 2:1-4).
Oh, how swift are the words of wisdom! How quickly the lesson is learned when God is the teacher! No interpretation is needed for understanding, no practice for using, no time for studying. The Spirit of Truth blows where He wills (cf. Jn 3:8), and the languages of each nation become common property in the mouth of the Church. So, from that day, the Gospel preaching has resounded like a trumpet. From that day, the showers of gracious gifts, the rivers of blessings, have watered every desert and all the dry land. To ‘renew the face of the earth’ (Ps 104:30), the Spirit of God ‘was moving over the face of the waters’ (Gen 1:2); and to drive away the old darkness, flashes of new light shone forth. By the blaze of those busy tongues, the Lord’s bright Word kindled speech into fire—fire to arouse the understanding and to consume sin. Fire has the power to enlighten and the power to burn.
God’s Word has authority, and it is ablaze with these and countless other proofs. Let us, all together, wake up to celebrate Pentecost. Let’s rejoice in honor of the Holy Spirit, through whom the whole Catholic Church is made holy, and every rational soul comes alive. He is the Inspirer of Faith, the Teacher of Knowledge, the Fountain of Love, the Seal of Chastity, and the Source of all Power. Let the spirits of the faithful rejoice. Let one God—Father, Son, and Holy Spirit—be praised throughout the world, by the confession of all languages. And may that sign of His presence, the likeness of fire, burn perpetually in His work and gift. The Spirit of Truth makes the house of His glory shine with the brightness of His light, and He wants nothing in His temple to be dark or lukewarm.”
-St. Leo the Great