The First Joyful Mystery of the Rosary is the Annunciation of the Lord, when the angel Gabriel appeared to the Blessed Virgin Mary to announce that she had been chosen by God to bear His Son.
This depiction of the Annunciation shows St. Gabriel the Archangel handing lilies to Our Lady. At the top of the window are two angels holding lilies. The translucent white petals of the Lily are symbolic of Mary's pure body.
The lower half of the picture depicts the angel Gabriel and the virgin Mary in an Annunciation scene recalling the first chapter in Luke’s Gospel. [LK 1:26-39] Notice the dove depicting the Holy Spirit overshadowing our blessed Mother.