Irenaeus on Pentecost

From Against Heresies

This is why the Lord had promised to send the Advocate: he was to prepare us as an offering to God. Like dry flour, which cannot become one lump of dough, one loaf of bread, without moisture, we who are many could not become one in Christ Jesus without the water that comes down from heaven. And like parched ground, which yields no harvest unless it receives moisture, we who were once like a waterless tree could never have lived and borne fruit without this abundant rainfall from above. Through the baptism that liberates us from change and decay we have become one body; through the Spirit we have become one in soul.

"The Spirit of wisdom and understanding, the Spirit of counsel and strength, the Spirit of knowledge and the fear of God" came down upon the Lord, and the Lord in turn gave this Spirit to his Church, sending the Advocate from heaven into all the world in which, according to his own word, the devil too had been cast down like lightning.