To what object is the narrator referring when she states in Chapter 19, "Never had I seen anything burn as brightly" (183)?

In Chapter 19, the old man and the narrator are slowly burning their wagon full of books as they walk from one bonfire to another to avoid the blasting heat of the central bonfire, where they could burn all their books at once and go home. As they approach the next bonfire, they see the library "completely engulfed in flames" (183) on the hillside where it stands. After noting that she has never "seen anything burn as brightly or as beautifully" as the library, the narrator adds that "the intense light and heat" drive out "all traces of the fear and sadness" (183) she had been feeling. When she goes on to name one of things that seems "to recede into the distance" as "things about which R had been trying to persuade" (183) her, it becomes clear that the narrator has lost her battle to retain control of her own mind in the face of the authoritarian state's methods.