孔子说过：“不愤不启，不排不发，举一隅不以三隅反，则不复也。”（《论语·述而》）意思是说，教育学生，不到他想把问题弄明白却弄不明白的时候，不去开导他。不到想说出来却说不出来的时候，不去启发他，你教他一方，他却不能由此推知其他三方，例如教他东方，不能由东方 Confucius said, “If you don’t feel angry, don’t give up, don’t give it a try if you don’t use it, then you won’t be able to do it again.” (“The Analects of Controversy”) means to educate the student, and he does not want to solve the problem. When he understands but cannot understand, he does not enlighten him. When you don’t want to say something and you can’t say it, don’t enlighten him. You teach him, but he can’t infer the other three parties. For example, if he teaches him the East, he can’t from the East.