Knowing is knowing, not knowing is not knowing, but knowing; It is a famous saying of Confucius, which is widely circulated. Later generations are used to remind people to treat knowledge with honesty, not to be hypocritical and arrogant, to develop a down-to-earth and earnest attitude, to seek truth from facts, to avoid recklessness and vanity, and to tell people to learn with an open mind and not to pretend to understand.
Extended explanation
Confucius advocated that "knowing is knowing, and not knowing is not knowing", and he kept his mouth shut about things he didn't know, so people with below-average intelligence certainly couldn't know everything. Admitting what you know and what you don't know is an honest attitude and the smartest attitude, except those mysterious things.
Only if you don't know can you know. Lv Duan and Song Taizong, ministers of the Song Dynasty, called him "not careless in small matters, not careless in big matters", which is a good example of abandoning "Xiao Zhi" as "great wisdom". Based on this, Zhang Shizhi defended Shanglin Wei in Hanshu, which was understood by Wendi.