On the one hand, it is the hard study and hard practice of Emperor Taizong, on the other hand, it is Wang Zhu's strict requirements and careful induction.
2. Original text
During the reign of Emperor Taizong, there was a king who wrote a book on the right army and won the law. He works for Hanlin. The emperor listened to politics, paid attention to writing, and sent several attendants to read books. Every time I think that I am not good, Taizong Yi deliberately goes to school. Ask again, as before. Or ask what it means and write: "The book is solid. If it is called goodness, I am afraid that the emperor no longer has this intention. " Later, the emperor's brushwork was excellent, surpassing ancient times, and the world thought it was conducive to rules.
3. Translation
During the reign of Song Taizong, a man named Wang Zhu studied Wang Xizhi's calligraphy, and soon grasped the essence of it, and was appointed as an academician by Emperor Taizong. Besides dealing with political affairs, Emperor Taizong also liked to practice calligraphy. A few times, he asked the chamberlain to take his own work for Wang Zhu to comment, but every time Wang Zhu said it was not good enough, so Taizong practiced more attentively. Emperor Taizong once again asked his attendants to ask Wang Zhu with his new words, and Wang Zhu's answer was still the same as at first. When asked about Wang Zhu's intention, Wang Zhu said: "The emperor's calligraphy is already very good, but if it is written well at once, I am afraid that the emperor will never be as diligent as before." After that, Tang Taizong's calligraphy was exquisite, surpassing many famous calligraphers before, and the world said that it all benefited from Wang Zhu's encouragement.