Where does "teacher, preach and teach to solve doubts" come from?

It is an argumentative essay written by Han Yu, a writer in the Tang Dynasty.

Han Yu, a vigorous advocate of the movement of ancient Chinese prose, is listed as the first of the "Eight Masters in Tang and Song Dynasties" and is called "Han Liu" with Liu Zongyuan. It advocates "taking literature as poetry", striving for novelty in poetry writing, and discussing more. The Complete Tang Poetry contains ten volumes of its poems. There is a collection of poems and essays edited by Mr. Changli.

The whole poem (excerpt) is as follows:

Ancient scholars must have teachers. Teacher, so preach and accept the industry to solve doubts. People are not born knowing, who can be without doubt? If you are confused and don't follow the teacher, it will be confusing, and you will never understand it. Before I was born, I learned the Tao before I was born, so I learned from it.

after being born in me, his knowledge of Tao also comes from me first, so I can learn from it. I'm a teacher, and I don't know that my years were born in me. Therefore, there is nothing expensive or cheap, nothing long or little, and the existence of Tao and the existence of teachers also exist.

The translation is as follows:

People who studied in ancient times must have teachers. Teachers can be relied on to impart truth, teach studies and answer difficult questions. People are not born to understand the truth, who can have no doubts? With doubts, if you don't learn from the teacher, those who become difficult problems will eventually fail to understand. Born in front of me, he understood the truth earlier than me, so I should follow him and regard him as a teacher;

Born behind me, if he understands the truth before me, I should follow him and regard him as a teacher. I'm learning from him. Who cares if he was born earlier or later than me? Therefore, regardless of status or age, the place where truth exists is the place where teachers exist.

Extended information:

Shi Shuo was written by the author during the 17th to 18th year of Zhenyuan (81-82), when he was a doctor of four schools in imperial academy. In the seventeenth year of Zhenyuan (81), the author who dismissed Xuzhou's official position and lived in Luoyang to preach and teach, was awarded the position of Dr. imperial academy in October of that year after two trips to Beijing.

At this time, the author is determined to use imperial academy as a platform to revitalize Confucianism and reform the literary world, so as to realize his ambition of serving the country. However, when I came to imperial academy to take office, I found that the imperial examination hall was dark, the government was corrupt, and the official system was full of drawbacks, which caused many students to lose confidence in the imperial examination and relax their studies. At that time, the upper class looked down on people who taught.

There is a concept of "being ashamed to be a teacher" in the scholar-bureaucrat class, which directly affects the teaching and management in imperial academy. The author is saddened by this and writes this article by answering Li Pan's question to clarify people's vague understanding of "seeking a teacher" and "being a teacher".

Baidu encyclopedia-Shi Shuo