4 Of Him it is said, “He ascended up on high, He led captivity captive, He gave gifts unto men.” What is, “He led captivity captive”? He conquered death. What is, “He led captivity captive”? The devil was the author of death, and the devil was himself by the Death of Christ led captive. “He ascended up on high.” What do we know higher than heaven? Visibly and before the eyes of His disciples He ascended into heaven. This we know, this we believe, this we confess. “He gave gifts unto men.”
What gifts? The Holy Spirit. He who gives such a Gift, what is He Himself? For great is God's mercy; He gives a Gift equal to Himself; for His Gift is the Holy Spirit, and the Whole Trinity, Father and Son and Holy Spirit, is One God. What has the Holy Spirit brought us? Hear the Apostle; “The love of God,” says he, “has been shed abroad in our hearts.” Whence, you beggar, has the love of God been shed abroad in your heart? How, or wherein has the love of God been shed abroad in the heart of man?
“We have,” says he, “this treasure in earthen vessels.” Why in earthen vessels? “That the excellency of the power may be of God?” Finally, when he had said, “The love of God has been shed abroad in our hearts;” that no man might think that he has this love of God of himself, he added immediately, “By the Holy Spirit, who has been given to us.” Therefore, that you may love God, let God dwell in you, and love Himself in you, that is, to His love let Him move you, enkindle, enlighten, arouse you.
Source: Sermons on Selected Lessons of the New Testament (New Advent)