Doomsday Book by Connie Willis

Roche turned and looked at Kivrin. "Are these the last days," he asked, "the end of the world that God's apostles foretold?"
Yes, Kivrin thought. "No," she said. "No, it's only a bad time. A terrible time, but not everyone will die. And there will be wonderful times after this. The Renaissance and class reforms and music. Wonderful times. There will be new medicines, and people won't have to die from this or smallpox or pneumonia. And everyone will have enough to eat, and their houses will be warm even in the winter." She thought of Oxford, decorated for Christmas, the streets and shops lit. "There will be lights everywhere, and bells that you don't have to ring."