Nativity of the Virgin

Domenico Ghirlandaio, Birth of Mary, fresco in the Cappella Tornabuoni, Santa Maria Novella, Florence, 1486-90
Today is the feast of the Nativity of the Virgin Mary, from which the date of the feast of the Immaculate Conception was derived -- December 8, nine months before September 8, just as Annunciation is March 25, nine months before Christmas. This beautiful depiction comes from Ghirlandaio's spectacular cycle on the Life of the Virgin in the Dominican church of Santa Maria Novella. The story appears to be taking place inside the Domus Aurea, the golden house of Nero, which had been excavated in Rome only a few years prior to this work. The Latin inscription that can be read on the cornice is --

NATIVITAS TVA DEI GENITRIX VIRGO GAVDIVM ANNVNTIABIT VNIVERSO MVNDO
It is the text of a Gregorian antiphon to the Virgin Mary, translated as "Your birth, O Virgin Mother of God, announced joy to the whole world." It was usually sung at the Magnificat of Vespers on September 8, and you can hear most of it here.