Christmas shopping, like shopping anywhere at any time, is not my idea of fun. Christmas shopping in a busy, rain swept, cold and crowded London is even less so.

Crossing Trafalgar Square I spied the National Gallery and retreated there for respite.

Soon I was inside the hushed and tranquil setting of an art gallery. Not just any art gallery either, but one with a long and illustrious history. It holds priceless works of art that people travel thousands of miles to behold.

Out of the cold and away from the endless tinsel-draped selling I moved through the galleries intent on finding the one painting I sought. I found it in the gallery’s medieval wing.

The Nativity by Piero della Francesca (c.1412–1492) is a special picture.

The Virgin in silent adoration gazes at her newborn Baby, who, placed upon the cold and hard earth, appears to be imploring her to lift him into her arms. To the right of the Virgin is a heavenly choir. Angels singing and strumming their lutes heralding the coming of the Christ, their faces express a mixture of transcendent awe and earthly rejoicing. Some of this angelic choir looks deep in contemplation while others appear as if they are announcing momentous news to the world, and as loudly as possible, namely, that the longed for Savior has come at last. Even the animals in the background appear to be joining in in this riotous heralding. This is a picture with sound and vision, if all in the eye of the beholder.

The Nativity has a quality with which its painter seemed to imbue all his works, that is a sense of mystery. Perhaps we should not be surprised that this picture contains a certain mystical dimension. It was inspired, so we are told, by the visions of a saint.

In the early 1370s, a Swedish woman, Birgitta Birgersdotter lived in Rome. While there she had a vision of the Nativity. She wrote it down describing how “the Virgin knelt down with great veneration in an attitude of prayer… [and] how she gave birth to her son from whom radiated such an ineffable light and splendour that the sun was not comparable to it.” Birgitta related how the moment of childbirth itself was sudden and instantaneous and so miraculously free of pain and evidence of childbirth that she found it difficult to comprehend how it had taken place. She beheld the Virgin, lost in contemplation, with the Child upon the ground, “naked and shining,” with the singing of “angels of miraculous sweetness and beauty” all around.

The earliest depictions of the Nativity that we still have are fourth-century carvings on Early Christian Roman sarcophagi. From the fifth century onwards, the reality of the Incarnation and the validity of the Virgin’s newly established title of Theotokos (Mother of God) was emphasised in art. By the sixth century another version of the Nativity appeared, first in Syria before becoming universal in the East throughout the Middle Ages, and then in Italy up until the late 14th century. Where previously the Virgin had been shown seated after the birth of Our Lord, now the Virgin was seen lying, with beside her in swaddling clothes the Child in a manger.

In the late 14th century a further transformation of the iconography of the Nativity occurred, especially in Italy. Now the Nativity scene was depicted as one of adoration: The Virgin kneeling before the Child — now painted naked and luminous — lying not in a manger but on the ground on a pile of straw or on the Virgin’s mantle.

This latter version almost certainly originates from the visions of Birgitta. This version appears to be universally adopted in Western Europe from the 15th century, a model widely seen in altarpieces and other devotional works dating from that period on.

Birgitta Birgersdotter would later be known to the world as St. Bridget of Sweden. Born around 1303 into a wealthy but pious family, at the age of 13 Birgitta married Ulf Gudmarsson, who was then 18. It was a happy marriage blessed with eight children, among them St. Catherine of Sweden.

Around 1344, in company with her husband, Birgitta made a pilgrimage to Santiago de Compostela. On the return journey her husband was stricken with an illness and shortly afterward died. Birgitta now became solely devoted to her Catholic faith. From childhood on she is said to have had visions and revelations; new ones now occurred. Many of these she wrote down.

Birgitta founded a new religious congregation, the Brigittines, or Order of St. Saviour. She journeyed to Rome in 1349 where but for a number of pilgrimages she remained until her death on July 23, 1373. Pope Boniface IX canonized her on Oct. 7, 1391.

Scholars think it is likely that the recorded visions of St. Bridget influenced artists like Piero who were to take inspiration from them when painting the Nativity scene. Some art historians have speculated that The Nativity was not for an altarpiece or a commission for a rich patron. Instead, they suggest that the painting was a wedding present to a young couple.

If that was the case, then The Nativity was a highly appropriate gift. The vision that inspired it was granted to a woman who knew the joys of a happy marriage. She was a woman who had also experienced the earthly limitations of human love in the untimely death of her husband. She knew the joys and pain of childbirth and motherhood. She was also a visionary and knew that whatever the joys of this world, they are but naught compared to the heavenly banquet to which all are invited.

And, so, on a darkening afternoon, there I stood in front of The Nativity some five centuries after it was painted.

Looking at the painting afresh, one is struck by its realism, and for all its angelic choir, the lack of the obviously supernatural in it. Yet for all that The Nativity does speak of another realm. In its harmony of the natural and the supernatural, human and the Divine, the painting offers a glimpse of the truth inherent in the Christmas scene, namely, that the world has changed and can never be the same again: The Word became flesh and dwelt amongst us.

A short time later, leaving the National Gallery I was once more back on the busy streets of London. The hustle and bustle had not abated, if anything it had grown yet more pronounced. For all that, I felt changed by my brief interlude in the gallery. Walking through the gathering gloom, the winking lights throughout the city no longer seemed to speak of money changing hands but instead sang a silent hymn to the reality presented in The Nativity that I had just contemplated.