Jesus's mother, Mary, appears in the gospels, but not a great deal and not in great detail. It’s a story of Jesus's life, so when she's mentioned it's usually around the drama of his birth, the birth of a virgin, and various moments in his ministry. It's interesting that, although the Gospels do not mention her much, from the second century on, there are tremendous stories that are told about her that fill in the back story. Who was she? Who were her parents? What was so special about her, that it made her the chosen one to give birth to a God? An even more important development occurs in the 4th century, when Christianity becomes licit, and later one of the religions of the Roman Empire. Emperor Constantine gathers a council to define the core beliefs of Christianity, and there again, Mary is mentioned in the creed that is defined. The creed is about Christ, but, nonetheless, it is mentioned that he was born of a virgin.

Mary is understood as an advocate for humanity, a mediator between the judging and scary God and the individual. As it was put at the time, her son will not refuse her anything, so if you pray to Mary and she passes on your plea, somehow, it'll be more successful. At the heart of it is, of course, the fact that through an understanding of Mary, obviously an understanding of Christ's saving humanity is enhanced, is made more interesting, and is communicated to people.

Even more so, it's through Mary that every Christian can associate his or her experience with the Christian story. People understand what motherhood is. Both the motherhood at the beginning of life, when the child is small and at the breast, like so many representations of Mary and her child, but also – and increasingly – Mary at the foot of the cross, imagining what it must have been for a mother to see her son suffering.

That quality, that pathos, that invitation to compassionately join, is the real driving force of so much art, music and poetry. The Stabat Mater, the mother stood at the foot of the cross, seeing her son suffer, is one of the most popular religious hymns. And indeed, in our corpus of classical music, it is extremely important because it captures something about the human condition, about loss. So, increasingly, Mary gets inserted into the absolute most important moments of the Christian story as taught to Christians in Europe.

Mary's characteristics are, above all, her humility and her utter purity. So pure was Mary understood to be, that it wasn't enough that she herself had never known a man and she conceived through the Holy Spirit, but that her own birth, the birth of Mary, was also deemed to be immaculate, without sin.

She was also a mum, like everyone else. There was great delight in describing her taking care of Jesus, cooking for him, teaching him his letters. Sometimes, he was naughty towards her. She takes him to school. All these experiences that people could hear and relate to.

But there's another quality that is also imputed to Mary: there are very strong traditions from around the year 500 that claim that Mary didn't die like anyone else. That, although she was human and thus could bear a human son, she fell asleep and ultimately was assumed into heaven, where she is queen of heaven alongside her son. So, in that way, she is elevated very much above the humanity with which she began. That meant that she was depicted as queen of heaven, as regal, wearing a crown and luxury goods. Not surprisingly, it was particularly in the patronage of kings and queens, and rich bishops that she was turned into works of art by these statues, illuminated manuscripts that use gold and silver. She was bejeweled as she was decorated in every way. But that is not something that most Christians were able to experience – it was the privilege of those on high.

The presence of a female figure at the heart of medieval Christianity had not only tremendous appeal to people at the time, but wherever there was an encounter between Christians and people they conquered, sought to convert, Mary played a really important role. We see it in two ways. We see it, for example, in Iberia, where throughout the 12th, 13th and until 1492, when the conquest of Iberia by Christian rulers was completed. Whenever Muslims came under Christian rule, there was an attempt to appeal to that already familiarity with Mary, in order to bring them over to Christianity, because Muslims revere Mary as well.

When the Franciscans follow the conquistadors to central and southern America in the 16th century, they bring this European experience with them. They understand the appeal that this loving mother can have to the bruised and traumatised communities of indigenous people that are now being Christianised. Mary becomes a much beloved figure and is truly promoted. There are translations into Náhuatl very early on, of miracles of the Virgin Mary, of hymns to the Virgin Mary, and there's a fruitful convergence of pre-existing devotions to two goddesses, to female godly figures in the indigenous cultures, that are connected with the figure of the Virgin Mary.

The images of Mary undergo an interesting historical development. The earliest examples of images of Mary are from the Byzantine world, from the eastern Mediterranean – the area where Christianity was born and developed – and a very strong mark upon how people envisaged Mary was planted by the imperial court in the Christian capital Constantinople – today’s Istanbul – for centuries.

There, the imperial family from the 4th century on, were leaders in Christian life. Imperial women, particularly, were very interested in the figure of Mary. So the sort of Mary that we see arising from the eastern Mediterranean, from these Byzantine lands is actually a very austere frontal, enthroned, queenly Mary that is quite solemn and often surrounded by saints and angels.

It's around 1000 that we see a new type of Mary, a new, softer, more maternal image. It engages with the baby. They sometimes touch each other. Sometimes, they look at each other. Sometimes, he's suckling from her breast. It's that new Mary that will develop into a memory of love and suffering and will be central to European Christianity.

Mary is important because she's a figure of femininity in the heart of a religion that gave very few women a role. That must have been, and must still be to many, very empowering and enriching. Mary also captured the fragility of the human condition and particularly loss, loss in war, loss in epidemic or suffering. After all, the figure of the pietà developed in late 13th century Europe. It’s a figure that is now used widely in the world to commemorate suffering, to remember victims, and that is very much still part of Mary's legacy.