Why did Su Shi say, "It's not enough to pay back the pen like a mountain. You have to read thousands of books to understand God"?

Even if bald pens pile up like mountains, they are not worth cherishing. Only by reading thousands of books thoroughly can we realize the creative realm of "connecting the gods".

Su Shi's nephews Liu Hong and Liu Ying appreciated his uncle's calligraphy and asked Su Shi for it. So Su Shi wrote two poems to apologize, saying that his calligraphy was not cherished enough. Only studying thousands of books is the realm that students should pursue. The epigram "Only when you read thousands of books can you understand the spirit" is a common language used by the ancients to persuade students to learn, and it is an integral part of our national cultural heritage. Du Fu also said, "Reading is like writing." This slogan, which calls for extensive reading, still has its practical significance in today's knowledge explosion, increasingly detailed social division of labor and narrower professional scope.