The following is a poem by Dongpo, which can be understood as some instructive revelations:

Dongpo's Dongpo Zhi Lin

Those who have no doubts about rough reading must teach those who have doubts, but there is no doubt that they will make progress here.

Zhu's Zhuzi School

You must doubt before you can make progress.

Everything must be taught with doubts in order to make progress, Zhu quoted this sentence.

If you are good at asking questions and know nothing, you must ask questions. Questions are like ladders, and the ladder of questions is the key to understanding.

Doubts will only increase.

Cheng Yi's "Henan Cheng's suicide note" Volume 5

Scholars must be suspicious before they can enter Germany.