HOW do we know what we know about the virginal conception of Jesus? Or his identity as Son of God, his birth in Bethlehem, his swaddling, his manger-bed? Only one person was present at all these events. That person is Mary. The annunciation was a dialogue between a woman and an angel. She must have described it to Joseph, because afterwards he was committed to helping to fulfil the prophecy of Micah (5.2).

Mary’s name is given three times in this lection: a remarkable number, given the paucity of named women in scripture more generally. Here is a detail to be cherished. But there is still so much that is obscure. We do not know who first wrote down her story of the encounter with Gabriel. Or how many more versions the story passed through before Luke gave it its final form in his Gospel.

What I say next is conjecture, but conjecture based on my having read a lot of ancient historical and biographical stories. And I am not alone in conjecturing this. I think that there is a shift from one source to another, between 1.26-80 and 2.4-5. Luke is laying aside one document and taking up a new one for the Bethlehem stage of the story.

This seems likely to me because he introduces Mary and Joseph in a way that sounds as if we are meeting them for the first, not the second, time. Luke tells us twice that Joseph had Davidic ancestry. He says that Joseph “went to be registered with Mary, to whom he was engaged and who was expecting a child”. But he needed to say only “he went with Mary”: we already know that they are engaged, and that she must be pregnant (this is not actually stated in the Gospel until 2.5).

So Luke gives us this information twice. Does it matter? In one sense, not at all. We cannot prove that he used more than one source. Even if we could, the evidence would cut both ways, just as it does with the four Gospels.

For some, discrepancies between the Gospels make their evidence unreliable. For others, me included, diversity of sources reveals that multiple communities of faith recorded and transmitted the nativity story. This makes the fact of an event’s happening more convincing, not less, even if some of the details cannot be reconciled. Stories that we tell in families or friendship groups take on just such a life of their own, each member telling the story in their own way. This is partly a fact of memory, partly because each of us has a unique viewpoint on events. Not everything is apparent from every viewpoint.

There is a more basic reason to trust what we read. Luke 2.19 records that “Mary treasured all these words and pondered them in her heart.” Here is evidence for a historical source, a proto-Gospel, even: events were committed to memory and their meaning was reflected on. Mary had not only her own experiences to base this on, but the shepherds’ report of an angelic message, too. Luke 2.51 confirms that this is not the only time that she “treasured” the events of her son’s infancy. Even “ordinary” parents will not quickly or easily forget such a time in their lives.

Many people note with interest the meaning of the name for Jesus’s birthplace. Beth-lehem means “house-of bread”. It is easy to see a link between the infant in the manger and the “living Bread that came down from heaven” (John 6.51). One might go still further, by thinking of Christ’s first dwelling-place, the Virgin’s womb, as his first incarnate home or “house”. That would make Mary a “house-of bread”, too.

Bread, to Christians, symbolises holy communion, the bread of life, before it symbolises anything else. Bread means experience of Jesus, contact with Jesus, accepting Jesus in one’s inner being. But, at this point in the story of Jesus, bread as a symbol looks backward to Beth-lehem more than forward to the bread of life.

Just now, I called Luke’s Gospel the “final form” of the nativity story. In reality, it is only the beginning. The story is being told, as authentically as it was by Mary, in every Christian church this day: not just when the Bible is read, but equally in every carol and anthem, every nativity play and Christmas crib, world without end.