The Archangel Gabriel announces to the Virgin that she will be visited by the Holy Spirit (represented as a dove) and bear the son of God. This event was predicted by the Old Testament prophet Isaiah; his words are inscribed on Mary's book. Mary's virginity is alluded to by the pure white lilies. This was the opening scene on the front predella, of Duccio's 'Maestà', which depicts Christ's childhood. Two other panels from the 'Maestà' are in the collection, 'Jesus opens the Eyes of a Man born Blind' and 'The Transfiguration'.
The'Maestà' is a monumental double-sided altarpiece ceremoniously delivered to Siena Cathedral in June 1311, and placed on the high altar. At the time, it was the richest and most complex altarpiece in Christendom, but it was dismembered in 1771, and although most of it is in the Cathedral Museum in Siena, several predella panels and pinnacles are dispersed in collections throughout the world. The front of the altarpiece shows the Virgin and Child enthroned with saints and apostles, with pinnacles depicting the last days of the Virgin. On the reverse the narrative runs from Christ's earthly ministry through his Passion to his appearances after the Resurrection.