A good book is beautifully written without folding paper, but it is not in the heart or in the hand.

Song Chen Shidao's "Talking about the Back Hill": "A good book does not choose paper and pen, but lies in the heart." It means that people with good calligraphy will not have too many requirements and picky about writing brushes. A master calligrapher can write better words than ordinary people even with an ordinary brush, while a good calligrapher should be familiar with the performance of various pens. Tools are important, but try not to let them bind you.