The window depicting the birth of the Lord begins at the top with a medallion which calls to mind the words of the Prophet Isaiah: “How beautiful upon the mountains are the feet of him who brings good tidings… who publishes salvation, who says to Zion, 'Your God reigns!'" (52:7).
At the center of the composition is the Christ Child, with a very bright face, a cross visible in His halo, dressed in white and sitting in a wooden manger. Mary sits to His left, holding Him. It’s interesting that her robe now has no embroidery: the artist is making sure that nothing distracts us from Jesus who is, quite properly, the center of attention. St. Joseph stands behind them, calm and protective, in a russet garment.
Three shepherds gaze in adoration at their King, a young boy playing a bagpipe, an old man with a beard, and a middle age man who has doffed his cap. On the floor of the stable rests a shepherd’s staff (which calls to mind both the 23rd Psalm and Christ as the Good Shepherd), while a single sheep looks up at Mary and the Child.
The dark sky at the top left, with shadowy shapes and trees and a lit candle to the bottom right, indicate that it is indeed night, recalling to mind the words of the old Christmas liturgy, that while all the world lay in slumber, the Word of the Lord leapt down from heaven. Finally, two candles are shown in the medallion below the picture. These may symbolize the Old and the New Covenants, or the dual nature of Christ as God and man, or (less likely because it would seem to make them equivalent in dignity) Mary and Jesus.