For around half the Christian population of Europe, the Virgin Mary was more than the Mother of God, Queen of Heaven, Star of the Sea, and so on. She was the focus of their devotion, a role model, the woman that they wanted to be. Dogma dictated that Mary couldn’t be a goddess, but she seems to have assumed some fairly divine properties.

One clue as to what may have happened here is given in Ferdinand Max Bredt’s unusual and undated painting of Sensual Pleasure and Peace of Mind, in which Eve stands on the left, holding the forbidden fruit and with the serpent’s long coils visible. On the right is Mary, dressed modestly in her traditional blue, her eyes cast up to heaven in prayer.

Beyond its obvious moralising message, with the femme fatale looking directly at the viewer trying to reassure us to ignore the snake, this brings together the two most prominent women in the Bible, one from the dawn of time, the other from the birth of Christ. Ignore that anachronism, and see how close Mary is to the snake.

As is fitting for a super-saint, the Virgin Mary is remembered on three Marian solemnities each year: Mary, Mother of God on New Year’s Day, her Assumption in August, and the Feast of the Immaculate Conception on 8 December. The last of those marks her conception free from Original Sin, which connects that feast to Eve and the serpent. It also happens to be an event which has been painted frequently.

Murillo’s Immaculate Conception (of Soult) from about 1678 is a fine example of about two dozen which he painted during his career.

The Virgin Mary, who normally looks up to God in heaven, is shown alone, usually wearing white robes with her signature blue cloak. She stands in the heavens, her arms crossed over her chest with the moon at her feet, surrounded by clouds, a golden light, and putti who are often winged. In some examples, there are twelve stars around Mary’s head, although not on this occasion.

This has also been shown in many statues of the Virgin Mary. But look more carefully at Mary’s feet and you may see something surprising.

This example of Our Lady of the Angels from Sineu on Mallorca features a bronze-coloured serpent with an apple stuck in its mouth, and one of Mary’s feet resting on it in her triumph over Original Sin.

This rather humbler statue of The Immaculate Conception in Augsburg-Kriegshaber, Germany, is very similar, with Mary’s feet pinning the brown snake to the ground.

This rather lovely Holy Family in Bamberg, Germany, shows Mary standing on a globe, around which is coiled a snake, again with an apple in its mouth.

Polychrome statues of the Virgin Mary remain common across the churches of Europe, and many of them show Mary standing on a snake. A frequent if even more puzzling alternative is for her feet to be resting on the heads of putti or infants, which resemble the human head sometimes attached to the snake’s body in depictions of the Fall of Man.

Paintings of the Virgin Mary standing on a snake are rather more unusual, but by no means rare among those showing the Immaculate Conception.

The first really good example that I have come across is Rubens’ Immaculate Conception from 1628-29, although I suspect that lesser painters had already been including the serpent under her feet. In addition to the standard symbols expected of this motif, the Virgin Mary’s right foot is pinning down a very obvious snake, which is holding a sprig of an apple tree in its mouth, with the fruit already bitten.

Almost a century later, the image of Mary walking on the snake seems to have enjoyed something of a comeback. Martino Altomonte’s Immaculate Conception from 1719 shows it quite clearly, within the more conventional iconography, although he hasn’t gone to such lengths to show the bite mark in the apple. You can also see how others came to depict Mary walking on the heads of putti, however strange that might appear.

From around the same time in the first half of the eighteenth century, this tondo attributed to Leonardo Antonio Olivieri adds a couple of attendant saints to form Immaculate Conception with Saint Anthony and Saint Camillo of Lellis. I’m not sure whether its body is coiled around the apple to the left, but this is yet another snake.

The latest in this series of paintings of The Immaculate Conception featuring the serpent of Original Sin is its most florid, made by Tiepolo in 1767-68. His Virgin Mary isn’t looking up to heaven, but appears to be relishing her role of vanquishing the snake of Eden. More curiously, tucked away at the foot, behind a palm tree, is a framed mirror, whose symbolism is open to speculation.

I have one last painting which, viewed apart from this series of Immaculate Conceptions, would have seemed the most enigmatic of all. It is also the precedent against which we should read them.

In 1605-06, Caravaggio painted what was expected to have been a fairly conventional depiction of the Virgin Mary, her mother Saint Anne, and the young Jesus Christ, for the altar of the confraternity of the Papal Grooms, in Saint Peter’s Basilica. What they got instead was his Madonna and Child with Saint Anne, which so shocked that it was only briefly shown in the parish church of Saint Anne in the Vatican, before being sold to Cardinal Scipione Borghese, in whose palace it still hangs.

At a time when even showing the Virgin’s feet was considered quite tacky, her low-cut dress was definitely beyond the pale, and Saint Anne is hardly flattered in her appearance. But look at what Mary’s left foot is doing, with support from Christ’s foot: treading on the head of a snake. Caravaggio too shows the Virgin Mary, here with the assistance of God the Son, vanquishing Original Sin.

Mainstream Christianity may have permanently excluded the goddess as a matter of dogma, but the triumph of the Virgin Mary over Original Sin is a significant reversal of the trap laid for Eve, the first woman, by Satan, the fallen (male) angel. But the woman won in the end.