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She stood so long and got so close to it that the guard got nervous and waved at her to step back.
During the four hours she stood there, she had this strange feeling that it was "something other then what it appeared to be." (p. 12)
As Hustvedt explains, the woman seems to be looking in a mirror, but there's so much light coming in the window that she almost seems to be looking out the window. She's holding up the necklace, but it is so subtly rendered the pearls don't seem to command much attention. She stands completely still, not really caught in a moment of action.
Unlike so many other Vermeers, this painting has an empty center. Vermeer had placed a map in the wall but x-rays show that he eliminated it. He covered much of the floor with great folds of cloth. He eliminated a musical instrument that had been on the chair. Nothing interrupts her gaze. She is not aware of any onlooker either.
As Hustvedt looks, she thinks about all those paintings in the genre of women at their toilet, but can't shake the feeling that this seems to be about something else, as well. The woman does not seem to be yearning for antyhing, nor is she caught up in her own vanity. All of a sudden, she says the word "Annunciation" popped into her mind. A pursuit of this possible allusion of Vermeer's sends her scurrying to art books, and she turns up several paintings in which Mary looks just as self-possessed and contemplative; her arms are raised this way, as well.
While Hustvedt is careful not to reduce the painting to this only possibility, she does feel there may be something suggested here by the artist. She notes the shape of the woman, who does look as though she might be pregnant. She is also somewhat amazed to notice what appears to be an egg in the window sill. Of course, she admits this is likely an architectural window detail, the painter doesn't include it in any of his other many-windowed paintings. Here's a slightly larger version; the egg is on the top of the sill by the drapes.
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So, what do you think? While others have pointed out that Vermeer manages, through his use of light, to make the everyday somewhat sacred, she suggests that in this painting he might be intending to provide an allusion that hasn't been noticed before. (By the way, Vermeer scholar Arthur Wheelock was there at the exhibit and she mentioned this idea to him. He agreed it was possible.)