The symbolism of snow includes purity, as in the miraculous snowfall of Our Lady of the Snows, St. Mary Major in Rome. Yet the turbulence of a winter storm brings to mind life's turbulence, the instability of earthly life.
Bl. Hildegard of Bingen used both images in her writing, but only one of them with reference to the Incarnation.
In her foremost work Scivias, describing a vision, she wrote, "Thus you see that a splendor white as snow and translucent as crystal shines around the image of that woman from the top of her head to her throat." Explaining that part of her vision, she wrote, "For the Church, who is the incorrupt Bride, is surrounded by apostolic teaching, which reveals the pure Incarnation of Him Who descended from Heaven into the Virgin's womb and Who is the strong and clear mirror of all the faithful." There, the snow's whiteness is used to describe the Church's apostolic teaching, which reveals Christ's pure Incarnation through the Virgin birth.
In contrast, in one of her letters to an Abbot, she wrote, "Your
mind is like a snow cloud, which rises above an airy cloud in which the
sun radiates, and sometimes it is like a windy cloud that brings
storms. The snow cloud is the weariness of an unstable mind. The airy
cloud, however, indicates unsullied knowledge acquired with the
patience of faith. But the windy cloud brings the disturbance of great
distress found in unquiet minds." (Letters, Vol. II) There, the snow cloud is used
to describe instability of mind, like the instability of the weather
when snow is in the forecast.
The instability of human hearts is easy to see in these days, as we watch the stock market roller coaster with each new day's glad or discouraging news. I suppose that most people can probably relate to Hildegard's description of an unquiet mind, comparing it to a windy snow cloud. But the snow itself she uses to describe the apostolic teaching that reveals the Incarnation to the Church. The soft purity of a blanket of white snow on the ground easily symbolizes something different from a volatile snow cloud.
In Hildegard's letter, the snow cloud symbolizes the unsettled mind of an individual with many things on his mind, despite the knowledge he has gained "with the patience of faith." She saw that "airy cloud" of "unsullied knowledge" as stabilizing. "The pure air," she told the abbot, "bestows dew, stable temperature, and rain: vegetation and flowers grow from it." Similarly, the "splendor white as snow" symbolizes that knowledge that can bring stability to a worried mind: the Church's apostolic teaching of the pure Incarnation of Christ, born of a Virgin.
Christmas draws nearer. The peaceful message of the birth of the blessed Babe is ever needed, especially in troubled times.