Pomona's bookshelf indeed had no books on the Sistine Chapel frescoes or William Blake, but she did have explanations of works in the Louvre Museum, which she used in her French classes.
The Virgin Marys painted by Raphael were famously beautiful, whether the one in the chair or the one in the fields.
Paintings of the Middle Ages were primarily religious in subject matter, and there were strict rules for depicting such themes. One obvious feature was that saints and angels had to be painted with thin halos above their heads to show that they were not ordinary people. During the Gothic era, the halos even had to be painted gold, forming golden discs.
In his early works, Raphael avoided this unnatural effect by painting only a faint, almost imperceptible ring, which did not count as violating religious doctrine.
In his later works, even that barely visible ring disappeared. The Virgin Mary became increasingly secularized. For example, when Raphael painted "The Beautiful Gardener," he used an everyday scene: Maria was reading when her little baby ran over to find his mother, so she closed the book and reached out to hug him.
This Virgin Mary was no longer the mother from medieval religious paintings who sat in a chair holding an infant, solemn-faced and dignified in serene stillness, whose love had to be expressed through red pigment. Painters of that time did everything they could to leave the blue outer robe of the Virgin Mary slightly open, revealing the red garment beneath. That, too, was dictated by doctrine, and painters could not alter it on their own.
There were no fluttering skirts in her portrait; every line either hung downward or was rigid. "The Beautiful Gardener" had an oval face, a small mouth, fair skin, and pale golden hair, with