Sì Wŭ Yī
Wan Shi Tong's Library held all the knowledge of the world, in its pure, complete form. The fox spirits traveled the world in search of true knowledge, never taking anything that had been censored or sanitized. After the war began, it became harder and harder to locate such tomes in the Fire Nation to replace the burned section. In addition, there is little to no information on Ba Sing Se.
When Professor Zei found the first mention of a war going on in the here and now, he stared at the book in horror, declaring, "There is no war in Ba Sing Se!"
Startled out of his rage against the Avatar and his companions, Wan Shi Tong glanced at the horrified professor and swiftly finished him off. It was a shame, really. Professor Zei seemed to understand the love of knowledge for knowledge's sake. But this was kinder in the end. The Fire Nation at least ended its propaganda at burning its books; Ba Sing Se burned the knowledge right out of its people's minds.
I'm normally not big on writing drabbles, but Banned Books Week seemed to merit one, as "City of Walls and Secrets" got my Bradbury senses tingling. According to Wikipedia and Shaun Garin (who takes Chinese), the title is Chinese for four-five-one, a reference to Ray Bradbury's Fahrenheit 451, from which my inspiration came.