This is the "An Old Woman with a Book" painted in the Dutch north by Gabriel Metsu. Created around 1660, it's an interesting example of how Metsu adapted ideas from other artists to create something unique. He borrows a device from Gerrit Dou, who had trained him in Leiden a few years earlier.
Dou's 'niche paintings' featured grand architectural frames that allowed for greater depth and visual interest. Here, Metsu uses this idea, but with a very different atmosphere. The old lady is absorbed and reflective, lost in thought as she ponders her book or perhaps prepares a medicinal concoction. The pestle and mortar, flagon, and worn pages of the book all suggest her connection to the medicinal arts.
Notice how the light highlights objects and figures in the foreground, while the chair and fireplace draw your eye deep into the background. Metsu's attention to detail is evident in the sheen on the metal pestle and mortar. He was a master at absorbing influences from other artists and making them his own.
An Old Woman with a Book hangs in The National Gallery on Trafalgar Square, London — free to enter. Point your phone at any artwork there and audioguide.london plays a free audio guide in six languages — no app download needed.