The story of the Annunciation in Luke 1:26-38 is elaborated in the Protevangelium of James, which adds a number of visual details that will appear in the art. Mary steps outside the house to fill a pitcher with water. She hears the first words of the angel's greeting and then returns inside, puts down the pitcher, takes a seat, and returns to her work of spinning purple thread for the Temple. Then the angel Gabriel appears and completes his message. The 3rd- or 4th-century Gospel of the Nativity of Mary adds that there was a great light when the angel appeared in the room.
Thus we have a number of elements that can be included in the composition: Mary, the angel, the pitcher, the spinning work, the seat, the light, and the two venues (outside the house and inside).
The Virgin Mary will be seen either sitting, standing, or kneeling. In the East, she either stands or sits (sometimes with a piece of cloth or spinning work on her lap) to the right of the angel, as in the image at left. Some early Annunciation mosaics in the West follow the Eastern usage of seating her in a throne-like chair (example).
In the West, Mary may express through gesture her humility in response to the angel's message (example), and a growing number of images show her reading or in prayer, often while kneeling at a prie-dieu that holds a volume of scripture (example). Sometimes the volume is open to Isaiah's prophecy (cached) that a virgin will conceive and bear a child. In late medieval images the prie-dieu may have a compartment holding more volumes of scripture -- the Word in written form, as the child in Mary's womb is the "Word made flesh" (John 1:14 -- cached).
Indeed, Annunciation images in the West use a number of devices to emphasize that the big story in what they are portraying is not the visit of an angel but the Incarnation. Light will stream down from heaven in the direction of the Virgin (example). Sometimes a dove flies down on this light or will hover above her head (example), representing the Holy Spirit and referring to the line in the Nicene Creed that states, "by the power of the Holy Spirit He became Man." In Paolo Veneziano's Getty Annunciation, at the moment of incarnation Mary holds a closed book to her belly, pregnant with "the Word made flesh."
Rounding out the Trinity and reflecting Luke's reference to "the power of the most high," medieval images add the Father, sometimes as a hand pointing down from the heavens and sometimes as a face looking from the sky (example).
The angel is conventionally seen in the left half of the image, often strongly separated from Mary by architectural or other elements. He usually has something in his hand -- originally a messenger's staff, but this evolves over time into a sceptre (expressing the "power of the Most High"?), a branch of lilies, or a palm branch. His words, Ave Gratia Plena, are often rendered in a scroll in or near his hand (example).
As time passed, Annunciation images discarded or adapted visual elements that had no raison d'être beyond being in the Protevangelium. The spinning work disappears, replaced by the prie-dieu and/or book. The outdoor venue is also gradually displaced by the indoor (though never entirely -- there is a twentieth-century "Annunciation at the Well" on one of the bronze doors of Santa Maria Maggiore in Rome). The indoor venue has the advantage that the moment being contemplated is the one in which the Incarnation actually occurs, with Mary's words "be it done unto me according to thy word."
The pitcher, which was never very popular in eastern images, becomes in the West a vase for lilies, symbols of Mary's purity (example).
One detail that is retained in many western images until the Renaissance is a secondary scene in which St. Joseph is at work (example) or being visited by an angel. The visit is recounted in both the Protevangelium and Matthew 1:18-21 (cached), and is a feature in some eastern icon types. The work is part of the story in the Protevangelium and the Gospel of Pseudo-Matthew: both narratives place Mary in Joseph's house on the day in question and say that at the time Joseph was away from home building houses.
There are a few cases in which a powerful donor is incongruously inserted into the Annunciation moment. Two such images are in Santa Maria sopra Minerva: a fresco by Filippo Lippi and a painting by Antonazzi Romano.
After the Annunciation and Joseph's dream explaining the situation, Mary and Joseph have a pregnancy to explain. In both the Protevangelium of James (chapter 16) and the Gospel of Pseudo-Matthew (chapter 12) they are summoned before the high priest, who orders them to drink "the water of drinking of the Lord," which supposedly causes a sign to appear on the face of a lying witness. No such sign appears, so the couple are exonerated. This episode is illustrated in a 6th century ivory in the Louvre.
In Genesis, God creates Adam on the 6th day. Starting at least in the 3rd century, Christian writers asserted that March 25, the sixth day of the solar year, was correspondingly the day of the Incarnation of Christ, the second Adam (as in Romans 5:14 -- cached). Giovanni di Paolo di Grazia even includes a scene of the expulsion from Eden in his Annunciation in order to underline this correspondence. The Nativity, which was not observed until the 4th century, was celebrated nine months later, on the 25th of December.
At left, a 7th-century silk
Byzantine reliquary, 8th/9th century (Annunciation in upper left)
French Romanesque sculpture
13th century mosaic in Rome
Messina, The Virgin Annunciate
Annunciation Relief with Eucharistic imagery
21st century bronze door
Early Texts Addressing the Annunciation:
The Gospel of Luke, 1:26-38 (cached)
The Protevangelium of James
The Third- or Fourth-Century Gospel of Pseudo-Matthew (cached), History of Joseph the Carpenter (cached), and Gospel of the Nativity of Mary (cached)
Homilies on the Annunciation by the 3rd-Century Alexandrine Gregory Thaumaturgus: First (cached), Second (cached), Third (cached), Fourth (cached)
The Golden Legend #51