Pentecost from the fathers

'And there appeared unto them cloven tongues like as of fire, and it sat upon each of them; and they were all filled with the Holy Spirit' (Acts 2:3-4). They partook of fire, not of burning but of saving fire; of fire which consumes the thorns of sins, but gives luster to the soul. This is now coming upon you also, and that to strip away and consume your sins which are like thorns, and to brighten yet more that precious possession of your souls, and to give you grace; for He gave it then to the Apostles. And He sat upon them in the form of fiery tongues, that they might crown themselves with new and spiritual diadems by fiery tongues upon their heads. A fiery sword barred of old the gates of Paradise; a fiery tongue which brought salvation restored the gift. St. Cyril of Jerusalem (Catechetical Lectures: Lecture 17 no. 15)