The Annunciation

13th century
Mosaic
Apse, Basilica of Santa Maria Maggiore, Rome

God's mouth emits the spiritus sanctus, punningly the Holy Spirit and "holy breath." Strikingly, God is pictured not as a hand or an old man but as the Son. Below, Gabriel greets Mary with the blessing gesture and she responds with a gesture that one historian says means reserve and detachment.

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Photographed at the basilica by Richard Stracke, shared under Attribution-NonCommercial-ShareAlike license.