What was the most difficult book in history?
This question was quite subjective because different people might have different understandings of what was difficult to understand. However, generally speaking, the most difficult books in history may vary from person to person, but some books may be considered difficult to understand because they involve certain philosophical, historical, cultural, language and other issues that require the reader to have a certain background knowledge and understanding ability to fully understand. For example, The Analects of Confucius was considered a difficult book because it contained a lot of discussions on moral, political, philosophical and other issues that required the reader to have deep thinking and understanding. In addition, Tao Te Ching was also a difficult book to understand because it involved philosophy, religion, morality and many other fields. It required the reader to have deep thoughts and experiences to truly understand. The most difficult book in history was a subjective question that depended on the reader's background knowledge and understanding.