Being happy if you don't know what you are doing will be so corrupt.

This passage is an evaluation of Wang Anshi, a representative figure who opposed political reform in the Northern Song Dynasty. Sima Guang said: "Understanding the chapter of Wen Fu means a lot, but being ignorant and happy, leaving loyalty, destroying Baidu, and even this." Fu Jie is Wang Anshi's word. Sima Guang said that Wang Anshi was "sexually ignorant" and "pleased to reject right and wrong", which was a very serious vicious criticism. The phrase "sexual ignorance" is like parents accusing their children of ignorance, and Sima Guang accusing Wang Anshi of being "ignorant" is hopeless, so there is nothing to do. To "drive away evil spirits with music", that is to say, it is similar to the "drive away evil spirits with music" of flies.