Why can Lu write independently before taking a seat?

First, the self-taught Water Margin stipulates that Lu is illiterate, but this does not mean that Lu can't read and write. At least when he became a monk, he listened to the words of the elder Zhizhen. When you are a monk, it is inevitable to recite the scriptures. Although Lu drinks and eats meat, it is certainly unreasonable if he does not perform the basic work of chanting. Although it is not shown in the article, it is reasonable to guess.

Moreover, even if he didn't learn to read on purpose, he would be more or less affected by being with a group of monks who can read all day. Just like many old people in modern times have never been to school or read books, but influenced by the new era and children, they can more or less know some basic vocabulary used in daily life.

In ancient times, few people were able to go to school, and most of them were social elites. But when a monk, in ancient times, he had to recite the scriptures every day. So how do people know the words in the scriptures? Of course, it's not just verbal. In fact, people who study in temples often take the lead in teaching literacy. Although it is not as professional as a private school, you can still recognize the words and meanings in the classics over time. Probably learned to write in this process.

Second, the author's mistakes "Water Margin" has been recognized by more than one author. Basically, there are two writers in front and behind, that is to say, Lu who can't read and Lu who can write. They are not from the same author, so it is likely that the author behind forgot this setting and mistakenly wrote Lu as a monk who can read and write.

Generally speaking, why Lu wrote in the book is not explained. He can only rely on readers to guess. It is precisely because there is no author's death setting that there is infinite possibility.