Gu's research summed up the two points mentioned above.

During Mr. Gu's journey, he must ask the older soldiers about his distress. If it doesn't agree with what he heard, he will go to the inn on the street to check the books. When traveling in the plain wilderness, you only concentrate on reciting classic works. If you forget, you have to go back to the inn on the street to look up books and read them carefully.