I always thought of this project as 'from Jewish maiden to global icon'," says Miri Rubin about Mother of God, her hugely ambitious "history of the Virgin Mary".
Rubin, a professor of early modern history at Queen Mary, University of London, is Israeli by birth and grew up in Jerusalem "without any sort of sensibility of Mary". Yet this was an excellent environment for the budding historian.
Not only is Jerusalem in many ways a medieval city, but anyone living there is well aware of the many competing Christian denominations ("there isn't one sect that is in charge"), including the Eastern churches often ignored by European writing on the Middle Ages.
Rubin says that researching and writing Mother of God proved "a real intellectual adventure" that required her to "stray well outside (her) comfort zone". After all, her next project is far more narrow in scope, focusing on a single 12th-century manuscript.
She brings to the task of studying Mary not the ardent faith of the believer, but the "informed distance" of the anthropologist or cultural historian.
"There are tens of thousands of books by people who are devoted to Mary and write about what that means for them," she explains. "But there aren't many history books. I attempt to understand the historical evolution of this figure, which is so compelling, despite her relative absence from the foundational texts of Christianity. It's also a book about the image of the mother, and what you can do with it."
Although it includes some interesting reflections on more recent times, the text's main coverage ends in about 1600, when the "traditional Mary" - already very rich and multifaceted - "received a major critique from Protestantism, so we don't have the one Mary, we have different Marys on the go.
"By 1600, readers have all the building blocks. Wherever they go, in whatever continent, they will be able to interpret enough of the iconography. They know Protestant Mary, they know Catholic Mary, they know European Mary, they know world Mary ... They will have learnt to think about the structures of Mary in the world. I don't yet see a new structure emerging."
Even subversive versions of Mary can build on what the tradition has to offer. Pop icon Madonna, for example, "is sufficiently familiar with a certain kind of American working-class Catholicism to make something of it and tease around it," Rubin says.
"At the start of her career, she dressed herself in frills and lingerie, which is not so far removed from how some modern American Marys are dressed up in churches. There's an iconography of excess that fed into (Madonna's) self-presentation, albeit in a naughty-girl sort of way."
On one level, Mother of God brings together an astonishing wealth of strange, moving, resonant and even repellent material about Mary in areas ranging from popular piety to high theological speculation.
Here are the clerics who dreamt of Mary squirting milk at them, and the unofficial shrines where women sought help if their breasts ran dry. Here are the devotional poems of the late Middle Ages in which Mary addresses her dying son with endearments and nicknames close to baby talk.
The book also discusses statues of the Black Virgin and the Vierge Ouvrante, which opens up to reveal a picture of God the Father and a procession of Teutonic knights. The fierce disputes about whether Mary should be honoured as Theotokos or Christotokos (Bearer of God or Bearer of Christ), and whether her swoon at the foot of the Cross merited a separate feast day, are also covered.
Although Mary can be portrayed as an inaccessible goddess, Rubin points out that sermons and vernacular dramas often depicted the Holy Family as the family next door. "They are very explicit about the circumstances: these are simple people, there's not much food in the pot, not much money in the pocket, dad teaches Jesus his job, mum teaches him his prayers.
"Protestants argued that this (Roman Catholic view) reduced them - they're just like everybody else. The story unfolds in instalments, with the sermons of the year. Imagine how much emotional investment people had in it when it came to the end, to this family they knew so well."
But what are we to make of all this? Rubin gives some striking examples of the use of Mary in anti-Jewish agitation and violence, notably in imagery of the triumphant church - "virginal, majestic, erect and truthful" - and the benighted synagogue. And she readily acknowledges that "the image of Mary has been very difficult for many women".
There may be no medieval equivalents to the recent "Mary ruined my life" memoirs of former convert girls who have rebelled against their background. Yet in a patriarchal society "Mary is turned into a means of policing chastity and directing women towards virginity or abstinence. She can be used - and indeed has been used - that way throughout Christian culture," says Rubin.
But although this is obviously true and important, it is far from Rubin's central thesis, since Mary can also be seen as "a resource for thinking about love and grief and mourning and victimhood".
The book's emphasis is firmly on how individuals and groups have done interesting and productive things with her archetype, rather than on how the powerful have used it to control others. This in turn leads to a concern with "just how much Mary means to men", says Rubin.
"It is easy to see Mary as a figure for women to be disciplined, educated into their role; that is usually what is documented. What struck me was how much Mary was a companion of some of the most rigorous thinkers of the Middle Ages", many of them celibates who left their mothers when young, living largely among men.
"The other thing I found fascinating was Mary, the mother figure - dare I say the Jewish mother figure? - prompting clever guys to be even cleverer, to show their cleverness, the competition between poets and thinkers about who could best (express) the vast contradictions that Mary represents. It's almost like a game between men around this figure of impossibility.
"This tells us about the ways in which what one might call the alpha-male experience - the experience of the top, privileged, most educated men - is very fragile. It needs the support of the most unsophisticated, primordial experience of the mother, the breast and maternal approval. It leads us to think about the whole relationship between mothers and sons, as sons cease being boys and become men."
A particularly striking example, she says, was the proposal in 15th-century Venice "to have an image of the Virgin at every street corner looking down on the populace", in an attempt to curb street crime and what we might call "laddish" behaviour.
This "figure of the mother who reminds young men to behave better" remains current, for example, in the Women in Black, whose vigils include witnessing Israeli border crossings to discourage soldiers from insensitivity or cruelty. To all of Mary's incarnations, then, we must now add one more: the medieval Venetian equivalent of the CCTV camera.