What does the joke Fool reveal and satirize?

This story tells people that there is a limit to doing anything. When it is just right, it is beautiful. Once overdone, it will go to the opposite side. If truth takes one step further, it will become fallacy.

Truth is a Chinese character, and Pinyin is dào lǐ, which means truth and right and wrong of Tao. Avenue gives birth to all things invisibly, runs all things mercilessly, and raises all things nameless. Those who are reasonable in the Tao are only natural. Those who follow the principles of nature will prosper by the way, while those who go against it will decline.