Source: "Xunzi Zidao": "So a gentleman knows what he knows, but he doesn't know what he doesn't know, but speaks; You can say you can, you can't say you can't, you can. If you want to speak, you will know, and if you go, you will be benevolent; Kindness alone is not enough, knowing that your husband is evil! "
Appreciation: Pay attention to words and deeds, and don't exaggerate your knowledge and skills. To use modern expression means to have a modest learning attitude.