This section of the Apocalypse describes how "a great sign appeared in heaven: A woman clothed with the sun, and the moon under her feet, and on her head a crown of twelve stars."(Apocalypse 12:1)
Medieval commentators interpreted this woman as representing the Virgin Mary. In the lines that follow, the woman is described as pregnant and in the throes of a painful labor. In the miniature, as John looks solemnly on, she clutches her swollen belly with both hands; white and red flames radiate from her, indicating that she is "clothed with the sun."